Wimbledon 2015: Roger Federer beats Sam Groth to reach last 16

Roger Federer has faced only two break points after three rounds at this year's Wimbledon

Roger Federer overcame the big-serving Sam Groth in four sets to reach the fourth round at Wimbledon

The Swiss second seed, 33, won 6-4 6-4 6-7 (5-7) 6-2 and faces Spanish 20th seed Roberto Bautista Agut next.

Despite firing the second-fastest serve in Wimbledon history with a 147mph effort, Australian Groth, 27, was outclassed by the seven-time champion.

Croatia's Marin Cilic beat American John Isner, but Frenchman Jo-Wilfried Tsonga lost to Ivo Karlovic.

Cilic's match was suspended at 10-10 in the fifth set on Friday because of bad light but resumed on Saturday, with the US Open champion winning two games for a place in the last 16.

Thirteenth seed Tsonga was beaten 7-6 (7-3) 4-6 7-6 (7-2) 7-6 (11-9) by 6ft 10in Croatian Karlovic, 36, who became the oldest man to reach the last 16 at Wimbledon for 39 years - since compatriot Niki Pilic in 1976.

Ivo Karlovic (right) is the oldest man to reach the last 16 of any Grand Slam since Jimmy Connors at the 1991 US Open

Karlovic will next face third seed Andy Murray after the Briton saw off Italy's Andreas Seppi in four sets.

France's Gilles Simon beat compatriot Gael Monfils in a five-set match that was moved from Court One and completed under the Centre Court roof at 22:28 BST.

Simon led by two sets to one when it switched courts and eventually prevailed 3-6 6-3 7-6 (8-6) 2-6 6-2.

He will now play Czech sixth seed Tomas Berdych, who beat Spaniard Pablo Andujar 4-6 6-0 6-3 7-6 (7-3).

Dustin Brown, who defeated Rafael Nadal in round two, lost 6-4 7-6 (7-3) 4-6 6-3 to Serbia's 22nd seed Viktor Troicki.

Troicki faces Vasek Pospisil in round four after the Canadian beat Britain's James Ward in five sets.

Federer pleased with first-week form

Federer lost his first set of the tournament against Groth but recovered to break the world number 66 twice in the fourth set.

The Swiss said of Groth: "He's got a big serve and is a good mover coming forward, but I need to focus on my serving games and I dealt with that very well.

"I'm very happy with the way I played and I'm very pleased with the first week."

A single break in each of the first two sets put Federer in control, as Groth failed to exert pressure on the 2014 finalist.

Federer was not troubled on his serve until the 12th game of the third set when Groth took him to deuce.

Although he held serve, the Swiss double-faulted at 3-3 in the resulting tie-break to hand Groth the mini-break and the Australian, who was looking increasingly comfortable at the net, took the set when Federer missed a forehand pass.

However, a forehand return allowed Federer to break early in the fourth set and he secured victory with another powerful return.

Quick finish takes Cilic through

Marin Cilic lost to eventual champion Novak Djokovic in the Wimbledon quarter-final in 2014

It had the potential to be another epic record-breaking match but Cilic quickly wrapped up victory against American Isner on Court One.

The pair featured in the two longest singles matches at Wimbledon - Isner taking 11 hours and five minutes to beat Frenchman Nicolas Mahut in 2010, while Cilic needed five hours and 31 minutes to overcome American Sam Querrey in 2012.

They had already been playing for four hours and 15 minutes when play was halted on Friday, but it only lasted another 16 minutes on the resumption.

Isner double-faulted on Cilic's fifth match point as the ninth seed won 7-6 (7-4) 6-7 (6-8) 6-4 6-7 (4-7) 12-10 in four hours and 31 minutes.

Tsonga out after triple tie-break loss

Tsonga held his serve for the entire match but still went out to world number 25 Karlovic as he lost three tie-breaks.

Karlovic sent down 41 aces and secured victory over the two-time Wimbledon semi-finalist on his third match point.

The Croatian appeared to double-hit a volley when Tsonga held set point in the fourth set tie-break, but the umpire was unmoved and the Frenchman did not complain.

Tsonga said: "It's the job of the umpire to see it. If he didn't see it I can't do anything about it. Even if I saw it I can't say anything."