Queen's 2017: Marin Cilic and Sam Querrey reach quarter-finals
|2017 Aegon Championships|
|Venue: Queen's Club, London Dates: 19-25 June|
|Coverage: Comprehensive live coverage on BBC One, BBC Two, Red Button, Connected TV and online daily|
Marin Cilic and Sam Querrey ensured there will be three former champions in the quarter-finals with victories on day four of the Aegon Championships.
Fourth seed Cilic beat 19-year-old American Stefan Kozlov 6-0 6-4.
"Serving well is they key on grass and I did that really well again today," said the 2012 champion, who is yet to face a break point.
American Querrey, the 2010 winner, beat Jordan Thompson - conqueror of Andy Murray - 7-5 (7-3) 3-6 6-3.
Bulgaria's Grigor Dimitrov, champion in 2014, is already through to the last eight, where he will face Russia's Daniil Medvedev.
The 19-year-old beat Australia's Thanasi Kokkinakis 6-2 6-2.
Spain's Feliciano Lopez saw off Frenchman Jeremy Chardy 6-1 7-6 (7-4) in the remaining second-round contest.
In the doubles quarter-finals, third seeds Jamie Murray and Bruno Soares beat Ryan Harrison and Michael Venus 7-6 (7-1) 4-6 10-6.
Serve key to Cilic chances
Croatia's Cilic, 28, is the highest seed left in the draw after Murray, Stan Wawrinka and Milos Raonic all lost on Tuesday.
"It happens quite often," said the former US Open champion.
"We are playing so many tournaments during the year and it's very rarely that all the top seeds are going through.
"So it's not easy, especially at a tournament like this where there's so many great players, great grass-court players.
"Considering also that it's one of the first weeks on grass, it's always very tricky."
Cilic has looked sharp in his opening two rounds and goes on to face American Donald Young for a place in the semi-finals.
Querrey ended the hopes of lucky loser Thompson, the Australian ranked 90 in the world who stunned five-time champion Murray.
"I don't feel like the win from seven years ago has any effect on how I play today," said Querrey, referring to his tournament win in 2010.
"That was fun to win, but seven years is a long time ago."
Teenager Medvedev races through
Kokkinakis, 21, had caused a major upset with his victory over Raonic on day two, but could not back up such a strong performance.
The Australian is ranked 698th following a succession of injuries and on Tuesday became the lowest-ranked player to beat a top-six opponent since 1994.
Medvedev proved much tougher opposition, however, repeating his win over Kokkinakis in the Netherlands last week as he fired down 13 aces.
"I'm happy I managed to show a very solid game, I was serving amazing," said the Russian, ranked 60th.
Federer joins top four for Wimbledon
Roger Federer took another step towards a ninth Halle title and boosted his Wimbledon hopes with victory over Germany's Mischa Zverev.
The Swiss, 35, won 7-6 (7-4) 6-4 to reach the quarter-finals in Germany, and ensure he will be seeded at least fourth for Wimbledon next month.
That means he will avoid meeting Andy Murray, Novak Djokovic or Rafael Nadal before the semi-finals at the All England Club.
Federer will play Germany's Florian Mayer in the last eight in Halle.