Djokovic v Haas
Novak Djokovic, who made just three unforced errors against Jérémy Chardy on Saturday, is in superb form but Tommy Haas, who has made a sensational comeback from injury, beat him in Miami earlier this year.
Tomic v Berdych
Bernard Tomic, who reached the quarter-finals two years ago, loves playing on grass and trounced Richard Gasquet in the third round. Tomas Berdych, however, is rediscovering the form that took him to the 2010 final.
Ferrer v Dodig
David Ferrer has been stretched in all three of his matches so far but his indomitable spirit has taken him through. Ivan Dodig will be playing in the fourth round of a Grand Slam tournament for the first time.
Seppi v Del Potro
Andreas Seppi has been taken the distance in five-set matches seven times this year and won them all but the Italian has lost all three of his previous meetings with Juan Martin del Potro, who has yet to drop a set.
Kubot v Mannarino
Has there been a Grand Slam fourth-round tie between two such unheralded opponents? Both Lukasz Kubot and Adrian Mannarino have benefited from opponents' injuries and one of them will be in Wednesday's quarter-finals.
Janowicz v Melzer
Jerzy Janowicz is potentially the biggest danger along Andy Murray's route to the final. The Pole has the big-hitting game to match his 6ft 8in frame, but comes up against a wily opponent in Jürgen Melzer.
Verdasco v De Schepper
Fernando Verdasco, the world No 7 four years ago, has made the last 16 for the fourth time after wins over Julien Benneteau and Ernests Gulbis. Big-serving Kenny de Schepper had won one match at Wimbledon until this year.
Youzhny v Murray
Andy Murray has beaten Mikhail Youzhny in their only two meetings, the latest four years ago. Youzhny, a great stylist, has plenty of experience but lacks the big weapons to trouble the very best.
Women's last 16 draw
S Williams v Lisicki
Serena Williams, the defending champion, has lost just three matches in the last 13 months and is showing no signs of weakness. Sabine Lisicki, who has a big serve, is at her best on grass but will that be enough?
Robson v Kanepi
Laura Robson is the first British woman through to the fourth round for 15 years. Kaia Kanepi has won four titles on the main tour and reached four Grand Slam quarter-finals but has struggled with injuries recently.
A Radwanska v Pironkova
Agnieszka Radwanska, last year's runner-up, was made to work hard by Madison Keys on Saturday. Tsvetana Pironkova is a Wimbledon specialist, having made one semi-final and one quarter-final.
Vinci v Li
Both are late developers. The 30-year-old Roberta Vinci has never gone beyond the fourth round here while Li Na has twice reached the quarter-finals. Li, 31, a former world No 4, won the French Open two years ago.
Puig v Stephens
Monica Puig lost in qualifying at Eastbourne but has made a sensational Wimbledon debut. Sloane Stephens beat Serena Williams at the Australian Open and is now a regular at the latter stages of Grand Slam events.
Bartoli v Knapp
Marion Bartoli, runner-up in 2007 after a stunning semi-final win over Justine Henin, has not dropped a set in her three matches so far. Karin Knapp had never won a match at Wimbledon before this year.
Kvitova v Suarez Navarro
Petra Kvitova, the 2011 Wimbledon champion, was stretched by Ekaterina Makarova in the third round but knows what it takes to win here. Carla Suarez Navarro is through to the fourth round for the first time.
Flipkens v Pennetta
Kirsten Flipkens reached a final in the Netherlands last month but had won only three matches in the main draw here until this year. Flavia Pennetta, a former world No 10, has made a strong comeback after injury.