Spain: Madrid - Doubles - Main |
| Quarter-finals | Koolhof W./Kubot L. | Mektic N./Pavic M. | 1:2 (3:6, 7:64, 7:10) | dettagli | 07.05.2021 |
| 1/8-finals | Koolhof W./Kubot L. | Demoliner M./Medvedev D. | 2:1 (7:5, 64:7, 10:3) | dettagli | 05.05.2021 |
| 1/16-finals | Koolhof W./Kubot L. | Tsitsipas Pe./Tsitsipas S. | 2:1 (6:4, 5:7, 10:6) | dettagli | 04.05.2021 |
Spain: Barcelona - Doubles - Main |
| 1/8-finals | Koolhof W./Kubot L. | Alcaraz C./Carreno-Busta P. | 0:2 (4:6, 1:6) | dettagli | 19.04.2021 |
Monaco: Monte Carlo - Doubles - Main |
| 1/8-finals | Fognini F./Schwartzman D. | Koolhof W./Kubot L. | 2:1 (1:6, 6:4, 10:7) | dettagli | 14.04.2021 |
| 1/16-finals | Mannarino A./Paire B. | Koolhof W./Kubot L. | 0:2 (62:7, 3:6) | dettagli | 13.04.2021 |
USA: Miami - Doubles - Main |
| 1/16-finals | Khachanov K./Rublev A. | Koolhof W./Kubot L. | 2:0 (6:4, 6:2) | dettagli | 25.03.2021 |
United Arab Emirates: Dubai - Doubles - Main |
| Quarter-finals | Koolhof W./Kubot L. | Krawietz K./Struff J-L. | 1:2 (7:5, 3:6, 3:10) | dettagli | 17.03.2021 |
| 1/8-finals | Koolhof W./Kubot L. | Melo M./Rojer J. | 2:1 (6:4, 0:6, 12:10) | dettagli | 15.03.2021 |
Netherlands: Rotterdam - Doubles - Main |
| Quarter-finals | Chardy J./Martin F. | Koolhof W./Kubot L. | 2:0 (6:4, 6:3) | dettagli | 03.03.2021 |
| 1/8-finals | McLachlan B./Nishikori K. | Koolhof W./Kubot L. | 1:2 (5:7, 6:3, 6:10) | dettagli | 02.03.2021 |
Australia: Australian Open - Doubles - Main |
| 1/8-finals | Ebden M./Smith J. P. | Koolhof W./Kubot L. | 2:0 (7:62, 6:4) | dettagli | 15.02.2021 |
| 1/16-finals | Kokkinakis T./Kyrgios N. | Koolhof W./Kubot L. | 0:2 (3:6, 4:6) | dettagli | 14.02.2021 |
| 1/32-finals | Behar A./Escobar G. | Koolhof W./Kubot L. | 0:2 (3:6, 4:6) | dettagli | 11.02.2021 |
Australia: Melbourne (Murray River Open) - Doubles - Main |
| Quarter-finals | Chardy J./Martin F. | Koolhof W./Kubot L. | 2:0 (7:68, 6:3) | dettagli | 06.02.2021 |
| 1/8-finals | Albot R./Gerasimov E. | Koolhof W./Kubot L. | 1:2 (2:6, 6:3, 7:10) | dettagli | 05.02.2021 |