Aegon Championships: Former champions Marin Cilic, Sam Querrey enter Queen's quarter-finals

London: Two former champions reached the quarter-finals of the Aegon Championships on Thursday, with fourth seed Marin Cilic overpowering American teenager Stefan Kozlov and Sam Querrey getting the better of Jordan Thompson.

Cilic, who claimed the title at the prestigious Wimbledon warm-up event in 2012, was imperious against Kozlov, winning 6-0 6-4 on Queen`s Club`s centre court.

Big-serving American Querrey, winner in 2010, cut short a dream week for Australian Thompson with a 7-6(3) 3-6 6-3 victory. Thompson, who only scraped into the draw as a lucky loser after failing to qualify, had knocked out world number one and five-times champion Andy Murray in the first round.

After the stifling temperatures of the first three days, fresher conditions returned to the west London club -- as well as a sense of tranquility after the series of shocks witnessed earlier in the week when Murray, Stan Wawrinka, Milos Raonic and Jo-Wilfried Tsonga all baled out early.

Cilic now looks like favourite for the title, especially after the clinical way he dispatched 19-year-old Kozlov.

The former U.S. Open champion romped through the first set in 24 minutes but was given more of a workout in the second.

Kozlov showed some tidy grasscourt skills of his own but never hinted at breaking the Croatian`s serve, which offered up only seven points to the American during the 65-minute contest.

Cilic, who beat John Isner in round one, will now take aim at his third American in a row in the quarter-finals when he takes on unseeded Donald Young.

Querrey, who caused the big shock at Wimbledon last year when he knocked out defending champion Novak Djokovic, failed to take any of the six break points that came his way in the first set against Thompson but edged the opener in a tiebreak.

Thompson struck back to level the match but Querrey recovered to break decisively in the fourth game of the decider and had enough firepower to claim victory.

"That was a long match for grass," Querrey, who fired down 15 aces, said on court. "It`s tricky out here, it was windy and Jordan had come off beating Andy so he was confident."

"It doesn`t get any easier though," the American said of his next opponent, the dangerous Luxembourg left-hander Gilles Muller who won the grasscourt title last week in Den Bosch.

Thanasi Kokkinakis will attempt to keep Australian hopes alive later on Thursday when he plays Russia`s Daniil Medvedev, while Spaniard Feliciano Lopez takes on Frenchman Jeremy Chardy.