Andy Murray expertly negotiated his way past Karen Khachanov to reach a sixth French Open quarter-final in seven years.

The big-hitting Khachanov had beaten Tomas Berdych and John Isner en route to a maiden last-16 grand slam appearance, but world number one Murray's game was an altogether different task and the Briton emerged a deserved 6-3 6-4 6-4 victor.

Murray showed signs that his early season problems with form and fitness are behind him with a fine straight-sets win over Juan Martin del Potro in round three.

On this occasion, Murray's performance was more workmanlike than stylish against a powerful 21-year-old opponent on Court Philippe Chatrier.

But the 30-year-old - despite being broken on a couple of occasions - was never truly troubled and a combination of brilliant defensive work and a superior clinical edge meant Murray booked a last-eight meeting with either Kei Nishikori or Fernando Verdasco.

Khachanov showed few signs of nerves early on, but Murray was quickly able to temper his opponent's style and the Briton pounced in game five.

A brilliantly timed forehand winner off Khachanov's serve brought up break point, before Murray's trademark defence forced the Russian to go wide and surrender serve.

Murray efficiently saw out the set, which ended with the first ace of the match, and a costly double fault from Khachanov saw the top seed break for a 2-1 lead in the second.

The momentum was briefly stemmed when Khachanov made the most of Murray's slight dip in standard in game six, but normal service quickly resumed as the Russian gave up a couple of costly errors and a double fault as Murray regained the advantage.

This time it was a lead Murray would not relinquish and he comfortably saw out the remainder of the set and, despite saving three break points, Khachanov put a backhand into the net to drop serve at the start of the third.

To his credit, Khachanov refused to yield and another Murray blip saw him level the set at 4-4.

Like in the second set, though, he immediately handed the advantage back to Murray, who served out at the first time of asking.

STATISTICAL BREAKDOWN 
Murray [1] bt Khachanov 6-3 6-4 6-4

WINNERS/UNFORCED ERRORS 
Murray – 29/14
Khachanov – 34/38

ACES/DOUBLE FAULTS 
Murray – 5/1
Khachanov – 1/6

BREAK POINTS WON 
Murray – 5/9
Khachanov – 2/2

FIRST SERVE PERCENTAGE 
Murray – 65
Khachanov – 58

PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE 
Murray – 70/75
Khachanov – 65/52

TOTAL POINTS 
Murray – 90
Khachanov – 70