| 8‑Nov‑1999 | Stockholm | Hard | SF | 71 | 68 | Magnus Gustafsson [SWE] d. Gambill | 6-0 2-6 7-6(4) | | 0.98 | 7.9% | 3.9% | 46.1% | 71.4% | 46.3% | 1/6 | 1:46 |
| 8‑Nov‑1999 | Stockholm | Hard | QF | 71 | 23 | Gambill d. (7)Mark Philippoussis [AUS] | 4-6 6-2 7-5 | | 0.94 | 10.3% | 5.6% | 45.8% | 77.6% | 46.6% | 7/9 | 1:59 |
| 8‑Nov‑1999 | Stockholm | Hard | R16 | 71 | 10 | Gambill d. (2)Tim Henman [GBR] | 7-5 6-3 | | 1.57 | 16.1% | 0.0% | 57.1% | 84.4% | 58.3% | 1/2 | 1:18 |
| 8‑Nov‑1999 | Stockholm | Hard | R32 | 71 | 49 | Gambill d. Arnaud Di Pasquale [FRA] | 6-2 6-3 | | 1.29 | 15.8% | 3.5% | 52.6% | 76.7% | 40.7% | 5/6 | 1:09 |
| 18‑Oct‑1999 | Lyon | Carpet | R32 | 58 | 26 | (12)Sebastien Grosjean [FRA] d. Gambill | 1-6 6-3 6-3 | | 0.78 | 8.6% | 9.7% | 44.1% | 73.2% | 40.4% | 6/10 | 1:53 |
| 18‑Oct‑1999 | Lyon | Carpet | R64 | 58 | 63 | Gambill d. Jan Kroslak [SVK] | 6-1 6-2 | | 2.12 | 21.3% | 6.4% | 51.1% | 87.5% | 60.9% | 1/1 | 0:56 |
| 11‑Oct‑1999 | Singapore | Hard | QF | 58 | 6 | (1)Marcelo Rios [CHI] d. (7)Gambill | 6-4 6-4 | | 0.61 | 10.2% | 1.7% | 54.2% | 78.1% | 51.9% | 2/4 | 1:10 |
| 11‑Oct‑1999 | Singapore | Hard | R16 | 58 | 76 | (7)Gambill d. Michael Chang [USA] | 6-2 7-6(4) | | 1.05 | 20.2% | 3.4% | 58.4% | 71.2% | 45.9% | 10/11 | 1:47 |
| 11‑Oct‑1999 | Singapore | Hard | R32 | 58 | 80 | (7)Gambill d. Justin Gimelstob [USA] | 7-6(2) 6-4 | | 1.35 | 7.0% | 2.8% | 60.6% | 81.4% | 53.6% | 3/4 | 1:37 |
| 4‑Oct‑1999 | Shanghai | Hard | QF | 59 | 65 | (6)Michael Chang [USA] d. (4)Gambill | 6-3 7-5 | | 0.63 | 18.6% | 4.3% | 57.1% | 77.5% | 36.7% | 4/6 | 1:41 |
| 4‑Oct‑1999 | Shanghai | Hard | R16 | 59 | 92 | (4)Gambill d. Antony Dupuis [FRA] | 6-3 6-4 | | 1.37 | 15.0% | 5.0% | 58.3% | 82.9% | 40.0% | 1/3 | 1:26 |
| 4‑Oct‑1999 | Shanghai | Hard | R32 | 59 | 1304 | (4)Gambill d. (WC)Yu Jr Wang [CHN] | 6-0 6-1 | | 3.63 | 14.7% | 8.8% | 61.8% | 95.2% | 61.5% | 0/0 | 0:42 |
| 30‑Aug‑1999 | US Open | Hard | R64 | 53 | 38 | Fabrice Santoro [FRA] d. Gambill | 6-4 6-2 3-6 6-7(7) 4-4 RET | | 0.94 | 7.9% | 3.4% | 53.9% | 74.0% | 42.7% | 12/18 | 3:37 |
| 30‑Aug‑1999 | US Open | Hard | R128 | 53 | 44 | Gambill d. Stefan Koubek [AUT] | 7-5 6-1 6-4 | | 1.51 | 15.7% | 7.2% | 66.3% | 81.8% | 53.6% | 2/3 | 1:39 |
| 23‑Aug‑1999 | Long Island | Hard | R32 | 54 | 12 | (5)Richard Krajicek [NED] d. Gambill | 6-4 6-3 | | 0.50 | 8.5% | 9.9% | 53.5% | 71.1% | 39.4% | 6/9 | 1:07 |
| 16‑Aug‑1999 | Washington | Hard | R64 | 53 | 83 | Kenneth Carlsen [DEN] d. (11)Gambill | 7-6(3) 4-6 6-4 | | 0.79 | 11.2% | 7.1% | 53.1% | 75.0% | 43.5% | 2/5 | 1:57 |
| 9‑Aug‑1999 | Cincinnati Masters | Hard | R32 | 50 | 21 | (15)Nicolas Lapentti [ECU] d. Gambill | 6-0 7-6(3) | | 0.43 | 12.7% | 4.8% | 57.1% | 69.4% | 37.0% | 1/4 | 1:03 |
| 9‑Aug‑1999 | Cincinnati Masters | Hard | R64 | 50 | 47 | Gambill d. Sjeng Schalken [NED] | 4-6 6-3 6-4 | | 1.38 | 17.5% | 3.8% | 56.3% | 80.0% | 54.3% | 2/5 | 1:48 |
| 2‑Aug‑1999 | Canada Masters | Hard | R32 | 49 | 36 | (17)Wayne Ferreira [RSA] d. Gambill | 7-5 3-6 7-6(8) | | 0.95 | 8.9% | 3.6% | 51.8% | 74.1% | 51.9% | 4/8 | 2:08 |
| 2‑Aug‑1999 | Canada Masters | Hard | R64 | 49 | 682 | Gambill d. (WC)Jocelyn Robichaud [CAN] | 6-0 6-0 | | 2.78 | 14.7% | 2.9% | 52.9% | 88.9% | 56.3% | 1/1 | 0:39 |
| 26‑Jul‑1999 | Los Angeles | Hard | R32 | 48 | 3 | (1)Andre Agassi [USA] d. Gambill | 6-2 6-2 | | 0.49 | 8.8% | 2.9% | 50.0% | 61.8% | 29.4% | 5/10 | 1:11 |
| 21‑Jun‑1999 | Wimbledon | Grass | R64 | 49 | 196 | (Q)Lorenzo Manta [SUI] d. Gambill | 6-4 6-4 3-6 6-7(4) 6-3 | | 0.90 | 10.7% | 4.4% | 58.7% | 77.7% | 52.9% | 10/14 | 2:58 |
| 21‑Jun‑1999 | Wimbledon | Grass | R128 | 49 | 41 | Gambill d. Franco Squillari [ARG] | 6-1 6-3 7-6(5) | | 1.65 | 9.8% | 2.9% | 57.8% | 86.4% | 51.2% | 5/6 | 2:00 |
| 14‑Jun‑1999 | Nottingham | Grass | R16 | 50 | 13 | (1)Greg Rusedski [GBR] d. Gambill | 4-6 6-4 7-5 | | 0.66 | 12.1% | 5.5% | 59.3% | 72.2% | 62.2% | 1/3 | 1:39 |
| 14‑Jun‑1999 | Nottingham | Grass | R32 | 50 | 123 | Gambill d. Chris Woodruff [USA] | 7-6(1) 6-4 | | 1.16 | 10.1% | 1.3% | 64.6% | 70.6% | 53.6% | 3/5 | 1:31 |
| 7‑Jun‑1999 | Queen's Club | Grass | R32 | 50 | 10 | (4)Mark Philippoussis [AUS] d. Gambill | 2-6 6-3 6-4 | | 0.98 | 18.1% | 4.8% | 57.8% | 81.3% | 42.9% | 6/8 | 1:37 |
| 7‑Jun‑1999 | Queen's Club | Grass | R64 | 50 | 221 | Gambill d. (Q)Michael Sell [USA] | 6-4 6-2 | | 2.87 | 16.7% | 7.1% | 52.4% | 86.4% | 80.0% | 0/1 | 1:09 |
| 24‑May‑1999 | Roland Garros | Clay | R128 | 50 | 5 | (5)Richard Krajicek [NED] d. Gambill | 7-6(4) 6-3 6-2 | | 0.79 | 4.3% | 2.2% | 55.9% | 73.1% | 41.5% | 5/10 | 2:10 |
| 10‑May‑1999 | Rome Masters | Clay | R64 | 51 | 5 | (5)Richard Krajicek [NED] d. Gambill | 6-0 3-6 6-1 | | 0.76 | 6.0% | 4.5% | 56.7% | 55.3% | 41.4% | 4/10 | 1:31 |
| 3‑May‑1999 | Hamburg Masters | Clay | R32 | 51 | 16 | (8)Gustavo Kuerten [BRA] d. Gambill | 6-4 6-4 | | 0.65 | 9.5% | 4.8% | 54.0% | 76.5% | 34.5% | 2/5 | 1:04 |
| 3‑May‑1999 | Hamburg Masters | Clay | R64 | 51 | 185 | Gambill d. (Q)Fredrik Jonsson [SWE] | 3-6 6-2 6-3 | | 1.06 | 11.4% | 4.5% | 51.1% | 73.3% | 51.2% | 3/5 | 1:48 |
| 26‑Apr‑1999 | Atlanta | Clay | R32 | 50 | 63 | Justin Gimelstob [USA] d. (7)Gambill | 6-0 6-4 | | 0.67 | 6.4% | 2.1% | 57.4% | 55.6% | 25.0% | 3/9 | 1:05 |
| 19‑Apr‑1999 | Orlando | Clay | R32 | 47 | 83 | Sargis Sargsian [ARM] d. (2)Gambill | 3-6 6-3 7-6(4) | | 0.81 | 7.2% | 4.1% | 54.6% | 83.0% | 45.5% | 5/7 | 1:57 |
| 15‑Mar‑1999 | Miami Masters | Hard | R64 | 44 | 33 | (29)Fabrice Santoro [FRA] d. Gambill | 7-5 6-2 | | 0.61 | 5.0% | 5.0% | 58.8% | 59.6% | 42.4% | 7/11 | 1:23 |
| 15‑Mar‑1999 | Miami Masters | Hard | R128 | 44 | 133 | Gambill d. (Q)Xavier Malisse [BEL] | 7-5 6-2 | | 1.74 | 5.5% | 0.0% | 45.5% | 68.0% | 73.3% | 5/7 | 1:07 |
| 8‑Mar‑1999 | Indian Wells Masters | Hard | R32 | 31 | 8 | (8)Richard Krajicek [NED] d. Gambill | 6-7(3) 7-5 7-5 | | 0.88 | 10.8% | 4.9% | 64.7% | 83.3% | 52.8% | 4/6 | 2:05 |
| 8‑Mar‑1999 | Indian Wells Masters | Hard | R64 | 31 | 66 | Gambill d. (Q)Jiri Novak [CZE] | 6-2 7-6(3) | | 1.37 | 10.6% | 4.5% | 54.5% | 77.8% | 53.3% | 2/4 | 1:11 |
| 1‑Mar‑1999 | Scottsdale | Hard | F | 45 | 91 | Gambill d. (Q)Lleyton Hewitt [AUS] | 7-6(2) 4-6 6-4 | | 0.98 | 9.5% | 3.4% | 53.4% | 75.8% | 48.1% | 5/8 | 2:21 |
| 1‑Mar‑1999 | Scottsdale | Hard | SF | 45 | 9 | Gambill d. (3)Andre Agassi [USA] | 5-4 RET | | 0.83 | 21.2% | 3.0% | 57.6% | 84.2% | 35.7% | 2/3 | 0:35 |
| 1‑Mar‑1999 | Scottsdale | Hard | QF | 45 | 68 | Gambill d. (WC)Justin Gimelstob [USA] | 4-6 6-4 6-1 | | 1.78 | 7.4% | 1.5% | 52.9% | 72.2% | 81.3% | 0/2 | 1:41 |
| 1‑Mar‑1999 | Scottsdale | Hard | R16 | 45 | 1 | Gambill d. (1)Pete Sampras [USA] | 4-6 6-3 6-4 | | 1.13 | 8.4% | 2.4% | 44.6% | 81.1% | 63.0% | 2/3 | 1:36 |
| 1‑Mar‑1999 | Scottsdale | Hard | R32 | 45 | 63 | Gambill d. Franco Squillari [ARG] | 3-6 6-3 6-4 | | 1.23 | 15.8% | 0.0% | 55.3% | 88.1% | 50.0% | 2/3 | 1:40 |
| 22‑Feb‑1999 | London | Carpet | R32 | 44 | 50 | Davide Sanguinetti [ITA] d. (WC)Gambill | 6-4 6-4 | | 0.68 | 17.8% | 5.5% | 50.7% | 78.4% | 44.4% | 11/13 | 1:12 |
| 15‑Feb‑1999 | Memphis | Hard | QF | 43 | 12 | (1)Todd Martin [USA] d. (7)Gambill | 3-6 7-5 7-6(7) | | 0.84 | 12.8% | 2.4% | 60.8% | 77.6% | 42.9% | 7/8 | 2:16 |
| 15‑Feb‑1999 | Memphis | Hard | R16 | 43 | 52 | (7)Gambill d. (9)Scott Draper [AUS] | 6-3 7-6(6) | | 1.39 | 26.6% | 3.1% | 65.6% | 76.2% | 68.2% | 3/3 | 1:19 |
| 15‑Feb‑1999 | Memphis | Hard | R32 | 43 | 114 | (7)Gambill d. (Q)Alex Calatrava [ESP] | 6-4 6-2 | | 1.53 | 30.0% | 6.0% | 66.0% | 78.8% | 64.7% | 0/0 | 0:57 |
| 8‑Feb‑1999 | San Jose | Hard | R32 | 37 | 75 | (WC)Justin Gimelstob [USA] d. (6)Gambill | 6-3 7-6(6) | | 0.89 | 13.2% | 4.4% | 48.5% | 78.8% | 45.7% | 4/6 | 1:38 |
| 18‑Jan‑1999 | Australian Open | Hard | R128 | 38 | 21 | Thomas Enqvist [SWE] d. Gambill | 6-3 7-6(5) 6-4 | | 0.92 | 14.3% | 2.4% | 47.6% | 83.3% | 40.9% | 2/7 | 2:00 |
| 11‑Jan‑1999 | Sydney | Hard | R16 | 37 | 13 | (7)Albert Costa [ESP] d. Gambill | 6-3 7-5 | | 0.68 | 8.3% | 0.0% | 61.7% | 81.1% | 39.1% | 5/7 | 1:10 |
| 11‑Jan‑1999 | Sydney | Hard | R32 | 37 | | Gambill d. (WC)Sandon Stolle [AUS] | 7-6(7) 2-6 6-1 | | 1.10 | 10.4% | 2.1% | 64.6% | 71.0% | 55.9% | 8/11 | 1:48 |