World number 88 Stan Wawrinka is through to his fourth quarter-final of the season after a hard-fought 7-6 7-6 win over the 4th seed Karen Khachanov in two hours and eight minutes. 2016 finalist served at only 49% but he saved five out of seven break points, breaking Karen twice from nine chances created and prevailing in tie breaks to enter the last eight.
Khachanov served for the opening set at 6-5 and had two set points in both sets but it wasn't to be for him in the end, losing focus in the crucial moments to end his campaign in the second round. Stan drew first blood in the fourth game after a poor forehand from Karen and the Swiss saved two break points in the following game to extend the lead to 4-1 with a service winner.
Wawrinka served for the set at 5-3 but he lost serve in the worst possible way after a double fault, allowing Karen to win four straight games when he sprayed a backhand error in the 11th game. The youngster was the one who had a chance to close the set on own serve but Stan broke back in the very last moment with a beautiful backhand cross court winner to level the score at 6-6 and set up a tie break.
There, Wawrinka moved 6-3 up with a single mini-break but he squandered all three set points to keep Karen in contention. The Russian saved two more set points and he wasted a couple of his own at 8-7 and 10-9 to lose the set 12-10 when he netted a forehand.
Khachanov fends off a couple of break points in the fifth game of the second set and he had a huge chance of sealing the set after a forehand winner in game 10 when he fired a forehand winner. Wawrinka stayed focused and he saved them to level the score at 5-5, earning the opportunity to move ahead in the next game after two break points up for grabs.
Karen saved them to remain on the positive side of the scoreboard and they had to decide the winner in the tie break, with the pressure on the home player. Stan opened it with a forehand winner and he scored two more mini-breaks to go 5-0 up after a backhand error from Khachanov.
The Swiss crossed the finish line with a backhand winner in the eighth point, cementing his place in the last eight where he will face Damir Dzumhur or Guido Pella. Wednesday's results: