Wimbledon 2013: Novak Djokovic joins Andy Murray, David Ferrer and Del Potro in last eight - and prepare to battle for semi-finals

Djokovic disposed of Haas with relative ease (Getty Images)

Amid the chaos and the carnage elsewhere, the top half of the men's draw is the only element that has shown some respect for the form-book. By the end of manic Monday, the four seeds due to reach the quarter-final had all done so.

Novak Djokovic led the way, without for once being at his supreme best as he defeated Tommy Haas 6-1 6-4 7-6. A first set lasting only 25 minutes was misleading in that Haas, who according to his countryman Boris Becker is playing the best tennis of his career at 35, had his chances. He became the first man to break the No 1 seed this tournament, doing so twice, but had to be content with that as well as a brave third set in which he saved a match point but made a couple of tired errors in the tie-break.

As the match grew more competitive there were some outstanding rallies, one of which ran to 37 strokes. "He's a grass court specialist so I'm really glad to have come through in three," Djokovic said. He will now play Tomas Berdych, the seventh seed, who beat him in the 2010 semi-final here.

The Czech ended Bernard Tomic's fine run by 6-7 7-6 6-4 6-4 in a match that took a while to catch fire. With Tomic's supporters' club, the Fanatix, having failed to get show court tickets, there was a distinct lack of atmosphere on Court One. For two sets the serve dominated and each man won a tie-break until the match went haywire with three breaks in five games, Berdych taking two of them and then the set. The fourth set also finished 6-4 in his favour, so the one remaining Australian in either draw is out.

One of the mysteries of tennis is how a player can find a match so difficult for an hour or more and then suddenly run away with it.

David Ferrer, the fourth seed, has become an expert in the genre over the past few days, twice struggling and then reducing opponents to gibbering wrecks.

The Spaniard had dropped at least one set in all three previous matches and on Saturday was 2-1 down to the Ukrainian Alexandr Dolgopolov before coming through the last two sets 6-1 6-2. Yesterday he was at it again, dropping the first set against Ivan Dodig of Croatia on a tie-break, drawing level on another one and then racing through the gears 6-1 6-1.

Not that he seemed to know the secret, unless it was all a matter of confidence. "When I won the second set, the third and the fourth, I receive better, I play more confident with my game," he said. "And of course him take down"; presumably meaning lost belief.

Ferrer had caused a certain amount of consternation by not turning up on the far-flung Court Two until almost ten minutes after the scheduled start-time of 11.30, which he insisted was nothing to do with needing treatment. Unlike many at this tournament he has not been making an excuse of injuries, despite the odd problem with his ankle and toe.

In the early games he regularly held break points without being able to capitalise and should never have been taken to a tie-break. He then went 0-3 down and never recovered, netting a backhand to concede the set in just under an hour. The second set tie-break went his way and from then on it was all downhill, dominating the next two sets while conceding only two games.

Dodig had reached new heights by playing in a fourth round of a Grand Slam, albeit with the benefit of two retirements by opponents, Philipp Kohlschriber and Igor Sijsling.

Ranked 49 in the world, he can look back with satisfaction, while Ferrer prepares for a quarter-final against the eighth seed, Juan del Potro, of whom he said: "He's a very great player. It's going to be difficult, and in grass court I think is more difficult. He play better than me in grass court."

Ferrer did, however, beat the Argentine in straight sets last year before losing to Andy Murray in the quarter-final, when three of the four sets went to tie-breaks.

Del Potro saw off Italy's Andreas Seppi, the 23rd seed and a five-set specialist who never looked like going that far this time. Three sets and saving three match points in the last of them was the best he could manage in going down 6-4 7-6 6-3. Thus Del Potro, the 2009 US Open champion, makes the last eight without having dropped a set. It is the first time he has done so in this tournament, although he was bronze medallist in the London Olympics here, beating Novak Djokovic.

"All players feel nerves towards the end of the match and he made fantastic winners but I played really well to win the last two points," he said. "I'm so happy to be in the quarters for the first time at Wimbledon. I'm improving on grass and I like it a lot."

His assessment of Ferrer, who leads him 6-2 on head-to-heads, was: "He's playing fantastic this season and I think he's the favourite but I like to play this on grass if my knee is okay. It's really painful but I'm having ice all the time."