Wimbledon 2018: Alexander Zverev knocked out but Juan Martin del Potro wins

Fourth seed Alexander Zverev has been knocked out of Wimbledon in the third round after a five-set defeat by qualifier Ernests Gulbis.

German Zverev led by two sets to one but lost 7-6 (7-2) 4-6 5-7 6-3 6-0.

The defeat means Zverev, 21, has still only reached one Grand Slam quarter-final, despite being regarded as one of the world's best young players.

Elsewhere, Japan's Kei Nishikori knocked Australian 15th seed Nick Kyrgios out in straight sets.

Nishikori, who has never made it past round four at Wimbledon, won 6-1 7-6 (7-3) 6-4.

The 24th seed won the first set in just 16 minutes before the match became more competitive but Nishikori won on his fourth match point.

Earlier, Juan Martin del Potro progressed to the fourth round for the first time since 2013.

The fifth seed won 6-4 7-6 (7-4) 6-3 against Benoit Paire, who repeatedly argued with the umpire during sets two and three.

It is the fourth time Argentine Del Potro has reached the fourth round but the first since being sidelined for nearly two years after wrist surgeries.

Only Rafael Nadal and Roger Federer are ahead of Zverev in the world rankings but he has once again failed at Grand Slam level.

The German has won eight ATP titles including three Masters crowns - the biggest regular tournaments after the four Grand Slams - but the only time he has progressed past the last 16 in 13 appearances at majors was at the French Open last month.

Zverev broke Gulbis when the Latvian was serving for the third set and then won three consecutive games to move two sets to one in front, at which point the momentum was with the German.

But in the following two sets Gulbis lifted his game, while Zverev's dropped, and the world number 138 won the match in a decider lasting just 22 minutes.

Gulbis, who has a career-high ranking of 10 in the world, will play Nishikori in the fourth round.

In a testing encounter, Del Potro had his serve broken in every set but saw off Paire in two hours 24 minutes on Court Two.

He seemed to lose focus in the third set when Paire continued to argue with the umpire.

Paire had initially been upset by the umpire not overruling an incorrect call by the line judge - although the decision did go the Frenchman's way after a Hawk-Eye challenge.

Paire continued to argue with the umpire and smashed his racquet when losing the second set, resulting in a code violation.

There was a lengthy delay in the final set after a spectator was given treatment after becoming unwell in the high temperatures but Del Potro wrapped up the match soon after.

He will play Gilles Simon in the fourth round after the Frenchman beat Matthew Ebden.

Elsewhere, Canadian 13th seed Milos Raonic completed his victory over Dennis Novak of Austria to progress to the fourth round.

The match was suspended on Friday because of bad light with the pair tied at one set all and Raonic leading 6-5 in the third set, but the 2016 runner-up broke serve immediately to win the set before comfortably sealing victory, 7-6 (7-5) 4-6 7-5 6-2.

Czech world number 93 Jiri Vesely knocked out 19th seed Fabio Fognini.

Russian 22-year-old Karen Khachanov progressed to the fourth round for the first time by beating 20-year-old American Frances Tiafoe in five sets, 4-6 4-6 7-6 (7-3) 6-2 6-1.