| 2‑Nov‑1998 | Paris Masters | Carpet | QF | 18 | 1 | (1)Pete Sampras [USA] d. Philippoussis | 6-3 6-3 | | 0.59 | 14.5% | 1.8% | 60.0% | 78.8% | 22.7% | 1/4 | 1:02 |
| 2‑Nov‑1998 | Paris Masters | Carpet | R16 | 18 | 7 | Philippoussis d. (7)Karol Kucera [SVK] | 6-4 4-6 7-5 | | 1.13 | 11.1% | 3.3% | 53.3% | 75.0% | 50.0% | 2/6 | 2:00 |
| 2‑Nov‑1998 | Paris Masters | Carpet | R32 | 18 | 11 | Philippoussis d. (10)Petr Korda [CZE] | 2-6 6-4 6-4 | | 1.20 | 10.1% | 5.1% | 59.5% | 76.6% | 53.1% | 3/6 | 1:36 |
| 2‑Nov‑1998 | Paris Masters | Carpet | R64 | 18 | 43 | Philippoussis d. Daniel Vacek [CZE] | 7-6(5) 7-6(6) | | 1.23 | 22.7% | 2.3% | 62.5% | 85.5% | 48.5% | 1/1 | 1:48 |
| 26‑Oct‑1998 | Stuttgart Masters | Hard | R32 | 19 | 8 | (10)Yevgeny Kafelnikov [RUS] d. Philippoussis | 4-6 6-4 7-6(4) | | 0.94 | 16.5% | 4.1% | 68.0% | 75.8% | 54.8% | 1/3 | 1:50 |
| 26‑Oct‑1998 | Stuttgart Masters | Hard | R64 | 19 | 40 | Philippoussis d. Fabrice Santoro [FRA] | 6-1 5-7 6-2 | | 1.62 | 17.3% | 6.7% | 60.0% | 80.0% | 56.7% | 1/3 | 1:36 |
| 19‑Oct‑1998 | Ostrava | Carpet | R32 | 19 | 65 | David Prinosil [GER] d. (6)Philippoussis | 6-3 6-7(8) 6-3 | | 0.80 | 20.2% | 3.2% | 68.1% | 76.6% | 53.3% | 4/6 | 1:45 |
| 28‑Sep‑1998 | Grand Slam Cup | Hard | SF | 15 | 3 | (2)Marcelo Rios [CHI] d. (3)Philippoussis | 7-6 6-3 6-4 | | | | | | | | | |
| 28‑Sep‑1998 | Grand Slam Cup | Hard | QF | 15 | 13 | (3)Philippoussis d. Jonas Bjorkman [SWE] | 4-6 7-6 6-1 | | | | | | | | | |
| 31‑Aug‑1998 | US Open | Hard | F | 22 | 3 | (3)Patrick Rafter [AUS] d. Philippoussis | 6-3 3-6 6-2 6-0 | (ch) | 0.49 | 3.7% | 9.6% | 51.9% | 64.3% | 35.4% | 14/20 | |
| 31‑Aug‑1998 | US Open | Hard | SF | 22 | 10 | Philippoussis d. (10)Carlos Moya [ESP] | 6-1 6-4 5-7 6-4 | (ch) | 1.27 | 14.7% | 7.7% | 65.7% | 88.3% | 38.8% | 2/3 | |
| 31‑Aug‑1998 | US Open | Hard | QF | 22 | 33 | Philippoussis d. Thomas Johansson [SWE] | 4-6 6-3 6-7(3) 6-3 7-6(10) | (ch) | 1.26 | 13.9% | 3.3% | 65.1% | 85.3% | 42.5% | 9/13 | |
| 31‑Aug‑1998 | US Open | Hard | R16 | 22 | 13 | Philippoussis d. (13)Tim Henman [GBR] | 7-5 0-6 6-4 6-1 | | 1.05 | 5.7% | 6.6% | 47.5% | 75.9% | 48.4% | 5/8 | |
| 31‑Aug‑1998 | US Open | Hard | R32 | 22 | 96 | Philippoussis d. Lucas Arnold Ker [ARG] | 7-6(5) 6-3 6-3 | | 1.76 | 11.2% | 3.7% | 57.0% | 86.9% | 56.5% | 2/3 | |
| 31‑Aug‑1998 | US Open | Hard | R64 | 22 | 97 | Philippoussis d. Sebastien Lareau [CAN] | 6-7(3) 6-3 6-3 6-4 | | 1.30 | 8.7% | 5.5% | 57.5% | 80.8% | 55.6% | 0/1 | |
| 31‑Aug‑1998 | US Open | Hard | R128 | 22 | 99 | Philippoussis d. Christian Ruud [NOR] | 7-5 6-4 6-3 | | 1.76 | 18.9% | 4.7% | 62.3% | 86.4% | 60.0% | 4/5 | |
| 17‑Aug‑1998 | Indianapolis | Hard | R16 | 22 | 11 | (6)Alex Corretja [ESP] d. (11)Philippoussis | 4-6 6-4 6-3 | | 0.78 | 12.4% | 5.6% | 60.7% | 75.9% | 45.7% | 6/8 | 1:54 |
| 17‑Aug‑1998 | Indianapolis | Hard | R32 | 22 | 79 | (11)Philippoussis d. Adrian Voinea [ROU] | 7-5 6-4 | | 1.43 | 26.7% | 8.3% | 55.0% | 93.9% | 51.9% | 0/1 | 1:10 |
| 17‑Aug‑1998 | Indianapolis | Hard | R64 | 22 | 125 | (11)Philippoussis d. Grant Stafford [RSA] | 6-3 6-2 | | 1.39 | 13.8% | 8.6% | 51.7% | 76.7% | 53.6% | 2/3 | 1:01 |
| 10‑Aug‑1998 | Cincinnati Masters | Hard | R32 | 22 | 16 | (14)Goran Ivanisevic [CRO] d. Philippoussis | 6-3 6-2 | | 0.59 | 12.2% | 4.1% | 65.3% | 59.4% | 47.1% | 2/5 | 0:59 |
| 10‑Aug‑1998 | Cincinnati Masters | Hard | R64 | 22 | 33 | Philippoussis d. Byron Black [ZIM] | 6-2 6-3 | | 1.09 | 25.0% | 6.3% | 53.8% | 76.7% | 45.9% | 11/11 | 1:16 |
| 3‑Aug‑1998 | Canada Masters | Hard | R16 | 25 | 5 | (3)Patrick Rafter [AUS] d. (14)Philippoussis | 6-3 6-3 | | 0.60 | 7.7% | 4.6% | 53.8% | 65.7% | 40.0% | 3/6 | 1:13 |
| 3‑Aug‑1998 | Canada Masters | Hard | R32 | 25 | 105 | (14)Philippoussis d. Wayne Black [ZIM] | 6-1 6-4 | | 1.31 | 37.3% | 8.5% | 59.3% | 94.3% | 33.3% | 1/1 | 1:00 |
| 3‑Aug‑1998 | Canada Masters | Hard | R64 | 25 | 226 | (14)Philippoussis d. (Q)Doug Flach [USA] | 6-4 6-3 | | 1.24 | 8.5% | 8.5% | 45.8% | 66.7% | 59.4% | 3/5 | 1:02 |
| 22‑Jun‑1998 | Wimbledon | Grass | QF | 28 | 1 | (1)Pete Sampras [USA] d. Philippoussis | 7-6(5) 6-4 6-4 | | 0.67 | 11.7% | 5.8% | 58.3% | 82.9% | 50.0% | 3/5 | 1:45 |
| 22‑Jun‑1998 | Wimbledon | Grass | R16 | 28 | 43 | Philippoussis d. Jason Stoltenberg [AUS] | 5-7 6-1 6-3 6-3 | | 1.22 | 6.3% | 5.6% | 58.0% | 79.5% | 45.0% | 4/6 | 2:24 |
| 22‑Jun‑1998 | Wimbledon | Grass | R32 | 28 | 342 | Philippoussis d. (Q)Daniele Bracciali [ITA] | 6-3 6-4 6-4 | | 1.34 | 20.4% | 6.6% | 57.7% | 87.3% | 51.7% | 7/7 | 1:52 |
| 22‑Jun‑1998 | Wimbledon | Grass | R64 | 28 | 128 | Philippoussis d. (Q)Alex Obrien [USA] | 6-7(3) 6-4 7-6(2) 6-3 | | 1.27 | 16.8% | 1.7% | 61.8% | 80.4% | 66.7% | 5/5 | 2:55 |
| 22‑Jun‑1998 | Wimbledon | Grass | R128 | 28 | 7 | Philippoussis d. (7)Yevgeny Kafelnikov [RUS] | 6-7(5) 7-6(1) 6-4 6-2 | | 1.37 | 12.3% | 8.6% | 56.4% | 84.8% | 38.0% | 4/8 | 2:40 |
| 8‑Jun‑1998 | Queen's Club | Grass | R64 | 22 | 92 | Jordi Burillo [ESP] d. (9)Philippoussis | 7-6(9) 7-5 | | 0.84 | 15.8% | 6.6% | 60.5% | 76.1% | 63.3% | 0/1 | 1:23 |
| 25‑May‑1998 | Roland Garros | Clay | R64 | 21 | 53 | Bohdan Ulihrach [CZE] d. Philippoussis | 3-6 6-7(2) 7-5 6-4 9-7 | | 1.20 | 8.9% | 4.8% | 57.5% | 83.3% | 45.2% | 3/8 | 3:22 |
| 25‑May‑1998 | Roland Garros | Clay | R128 | 21 | 98 | Philippoussis d. (LL)Oliver Gross [GER] | 6-1 7-5 6-4 | | 1.24 | 10.9% | 5.0% | 57.4% | 86.2% | 44.2% | 3/4 | 1:37 |
| 18‑May‑1998 | Dusseldorf | Clay | RR | 21 | 49 | Philippoussis d. Jim Courier [USA] | 6-3 6-4 | | 2.44 | 22.9% | 6.3% | 66.7% | 87.5% | 75.0% | 0/0 | 1:07 |
| 18‑May‑1998 | Dusseldorf | Clay | RR | 21 | 7 | Philippoussis d. Jonas Bjorkman [SWE] | 6-3 6-4 | | 1.28 | 13.4% | 4.5% | 50.7% | 82.4% | 48.5% | 3/4 | 1:16 |
| 18‑May‑1998 | Dusseldorf | Clay | RR | 21 | 2 | Petr Korda [CZE] d. Philippoussis | 6-3 3-6 6-2 | | 0.82 | 8.6% | 5.4% | 58.1% | 70.4% | 41.0% | 11/15 | 1:42 |
| 11‑May‑1998 | Rome Masters | Clay | R64 | 22 | 11 | (11)Richard Krajicek [NED] d. Philippoussis | 5-7 7-6(4) 6-1 | | 1.04 | 6.3% | 2.5% | 39.2% | 80.6% | 62.5% | 2/5 | 1:52 |
| 27‑Apr‑1998 | Munich | Clay | R16 | 18 | 38 | Nicolas Escude [FRA] d. (5)Philippoussis | 6-4 7-6(4) | | 0.64 | 11.7% | 13.0% | 35.1% | 81.5% | 46.0% | 4/6 | 1:23 |
| 27‑Apr‑1998 | Munich | Clay | R32 | 18 | 41 | (5)Philippoussis d. Julian Alonso [ESP] | 7-5 6-4 | | 2.37 | 39.6% | 9.4% | 56.6% | 96.7% | 69.6% | 1/1 | 0:56 |
| 20‑Apr‑1998 | Monte Carlo Masters | Clay | R16 | 17 | 66 | (WC)Boris Becker [GER] d. (13)Philippoussis | 6-1 6-1 | | 0.35 | 7.1% | 7.1% | 54.8% | 43.5% | 42.1% | 3/8 | 0:50 |
| 20‑Apr‑1998 | Monte Carlo Masters | Clay | R32 | 17 | 22 | (13)Philippoussis d. Magnus Norman [SWE] | 6-4 6-3 | | 1.50 | 9.5% | 0.0% | 57.1% | 72.2% | 66.7% | 5/5 | 1:41 |
| 20‑Apr‑1998 | Monte Carlo Masters | Clay | R64 | 17 | 41 | (13)Philippoussis d. Julian Alonso [ESP] | 7-6(9) 4-6 6-4 | | 1.08 | 15.4% | 7.7% | 64.4% | 74.6% | 35.1% | 1/7 | 2:01 |
| 16‑Mar‑1998 | Miami Masters | Hard | R64 | 16 | 105 | (Q)Steve Campbell [USA] d. (15)Philippoussis | 3-6 6-3 6-3 | | 0.82 | 15.0% | 8.0% | 57.0% | 71.9% | 37.2% | 7/12 | 1:37 |
| 9‑Mar‑1998 | Indian Wells Masters | Hard | R64 | 14 | 126 | (WC)Jan Michael Gambill [USA] d. (12)Philippoussis | 7-6(7) 5-7 7-6(6) | | 1.10 | 16.0% | 6.7% | 62.2% | 75.7% | 51.1% | 4/7 | 2:23 |
| 2‑Mar‑1998 | Scottsdale | Hard | R16 | 13 | 40 | Tommy Haas [GER] d. (1)Philippoussis | 5-7 6-2 6-0 | | 0.72 | 3.6% | 8.4% | 57.8% | 58.3% | 40.0% | 4/10 | 1:34 |
| 2‑Mar‑1998 | Scottsdale | Hard | R32 | 13 | 92 | (1)Philippoussis d. (Q)Franco Squillari [ARG] | 6-2 7-5 | | 1.43 | 16.9% | 8.5% | 62.7% | 83.8% | 59.1% | 1/1 | 1:01 |
| 16‑Feb‑1998 | Memphis | Hard | F | 16 | 5 | (4)Philippoussis d. (2)Michael Chang [USA] | 6-3 6-2 | (ch) | 1.58 | 28.6% | 7.1% | 58.9% | 87.9% | 47.8% | 4/4 | 1:19 |
| 16‑Feb‑1998 | Memphis | Hard | SF | 16 | 7 | (4)Philippoussis d. (1)Marcelo Rios [CHI] | 6-4 7-6(5) | | 1.23 | 26.2% | 3.1% | 64.6% | 85.7% | 60.9% | 1/1 | 1:16 |
| 16‑Feb‑1998 | Memphis | Hard | QF | 16 | 30 | (4)Philippoussis d. (5)Thomas Enqvist [SWE] | 3-6 6-2 7-6(3) | | 0.87 | 25.6% | 5.6% | 62.2% | 85.7% | 47.1% | 3/5 | 1:31 |
| 16‑Feb‑1998 | Memphis | Hard | R16 | 16 | 57 | (4)Philippoussis d. (13)Sjeng Schalken [NED] | 6-4 6-4 | | 1.51 | 16.7% | 3.7% | 63.0% | 82.4% | 65.0% | 0/0 | 1:10 |
| 16‑Feb‑1998 | Memphis | Hard | R32 | 16 | 88 | (4)Philippoussis d. Wayne Black [ZIM] | 6-1 6-2 | | 1.97 | 39.1% | 2.2% | 67.4% | 83.9% | 53.3% | 2/2 | 0:47 |
| 9‑Feb‑1998 | San Jose | Hard | R32 | 17 | 75 | Vincent Spadea [USA] d. (4)Philippoussis | 6-4 6-3 | | 0.88 | 8.5% | 6.4% | 72.3% | 73.5% | 38.5% | 1/4 | 0:59 |
| 19‑Jan‑1998 | Australian Open | Hard | R64 | 17 | 47 | Hicham Arazi [MAR] d. (15)Philippoussis | 1-6 6-2 4-6 6-1 9-7 | | 0.83 | 8.8% | 1.8% | 69.9% | 72.2% | 35.3% | 5/10 | 2:57 |
| 19‑Jan‑1998 | Australian Open | Hard | R128 | 17 | 110 | (15)Philippoussis d. Alex Calatrava [ESP] | 7-6(0) 6-4 7-6(4) | | 1.55 | 18.3% | 0.8% | 79.2% | 88.4% | 60.0% | 0/0 | 1:51 |