London - Defending champion Novak Djokovic of Serbia has been up against it in his match against South Africca's Kevin Anderson at the Wimbledon tournament.
Anderson grabbed the first two sets 7-6, 7-6 before Djokovic started firing on all cylinders. He won the third set 6-1 and the fourth 6-4.
The match will continue on Tuesday.
Meanwhile seven-time Wimbledon champion Roger Federer is back in the quarter-finals at the All England Club.
Federer beat 20th-seeded Roberta Bautista Agut 6-2, 6-2, 6-3 on Centre Court, putting him in the quarter-finals at the grass-court major for the 13th time.
Federer, who lost in last year's final to Djokovic, needs one more Wimbledon title to break the record he holds with Pete Sampras and 1880s player Willie Renshaw.
Gilles Simon will be playing in the Wimbledon quarter-finals for the first time.
The 12th-seeded Frenchman beat 2010 Wimbledon runner-up Tomas Berdych 6-3, 6-3, 6-2.
Simon has only once before reached the quarter-finals at a major tournament, getting that far at the 2009 Australian Open.
Cilic in quarters
And U.S. Open champion Marin Cilic made his way into the quarters by beating Denis Kudla of the United States.
Cilic won 6-4, 4-6, 6-3, 7-5 on Court 3 to reach the quarterfinals at the All England Club for the second straight year.
Results at Wimbledon on Monday, the seventh day of the 2015 championships at the All England Club (x denotes seeding):
Marin Cilic (CRO x9) bt Denis Kudla (USA) 6-4, 4-6, 6-3, 7-5
Stan Wawrinka (SUI x4) bt David Goffin (BEL x16) 7-6 (7/3), 7-6 (9/7), 6-4
Richard Gasquet (FRA x21) bt Nick Kyrgios (AUS x26) 7-5, 6-1, 6-7 (7/9), 7-6 (8/6)
Vasek Pospisil (CAN) bt Viktor Troicki (SRB x22) 4-6, 6-7 (4/7), 6-4, 6-3, 6-3
Andy Murray (GBR x3) bt Ivo Karlovic (CRO x23) 7-6 (9/7), 6-4, 5-7, 6-4
Gilles Simon (FRA x12) bt Tomas Berdych (CZE x6) 6-3, 6-3, 6-2
Roger Federer (SUI x2) bt Roberto Bautista (ESP x20) 6-2, 6-2, 6-3
Suspended due to darkness:
Novak Djokovic (SRB x1) level with Kevin Anderson (RSA x14) 6-7 (6/8), 6-7 (6/8), 6-1, 6-4
Serena Williams (USA x1) bt Venus Williams (USA x16) 6-4, 6-3
Victoria Azarenka (BLR x23) bt Belinda Bencic (SUI x30) 6-2, 6-3
Maria Sharapova (RUS x4) bt Zarina Diyas (KAZ) 6-4, 6-4
Coco Vandeweghe (USA) bt Lucie Safarova (CZE x6) 7-6 (7/1), 7-6 (7/4)
Garbie Muguruza (ESP x20) bt Caroline Wozniacki (DEN x5) 6-4, 6-4
Timea Bacsinszky (SUI x15) bt Monica Niculescu (ROM) 1-6, 7-5, 6-2
Madison Keys (USA x21) bt Olga Govortsova (BLR) 3-6, 6-4, 6-1
Agnieszka Radwanska (POL x13) bt Jelena Jankovic (SRB x28) 7-5, 6-4