Andy Murray avoided another French Open marathon by maintaining his perfect record against Ivo Karlovic with a straight-sets victory to ease into the fourth round.

Murray needed five sets to beat Radek Stepanek and Mathias Bourgue, but the second seed took only an hour and 58 minutes to see off Karlovic 6-1 6-4 7-6 (7-3) on  Court Suzanne-Lenglen.

Two-time grand-slam champion Murray teetered on the brink of a Roland Garros exit in his first two matches, but the Brit coasted to a seventh victory out of seven against the lofty Croatian on Friday.

Karlovic came through a gruelling five-setter against Jordan Thompson to become the oldest player to reach round three of a grand slam in 25 years, but that appeared to have taken its toll on the big-serving 37-year-old.

It was Murray's serve that proved to be more potent as he did not face a solitary break point and stayed in the hunt for a first French Open title, with John Isner or Teymuraz Gabashvili awaiting in the last 16.

World number two Murray made a blistering start, breaking by lifting a perfectly executed lob over the imposing frame of Karlovic to take a 2-0 lead.

Karlovic was unable to wind up his vicious serve and two double faults gifted Murray another break point, which he won with a fizzing forehand that the veteran was unable to return.

Murray served out the set to love after a stiff-looking Karlovic finally got on the board and the Scotsman carried on where he left off with a break in the opening game of the second set, forcing another error from his out-of-sorts opponent.

The world number 28 was given a let-off when Murray was unable to put away a forehand pass for a 4-1 lead after earning two break points, but the favourite was soon sitting down with a two-set lead.

Karlovic dug deep to save two break points in the fifth game of a third set which went with serve, but Murray claimed two mini-breaks in the tie-break with sublime winners and advanced when the 27th seed fired a forehand long.

STATISTICAL BREAKDOWN
Murray [2] beat Karlovic 6-1 6-4 7-6 (7-3)

WINNERS/UNFORCED ERRORS
Murray - 34/4
Karlovic - 37/21


ACES
Murray - 14
Karlovic - 8


BREAK POINTS WON
Murray - 3/10
Karlovic - 0/0

FIRST SERVE PERCENTAGE
Murray - 75
Karlovic - 64


PERCENTAGE POINTS WON ON FIRST/SECOND SERVE
Murray - 87/57
Karlovic - 77/47


TOTAL POINTS
Murray - 98
Karlovic - 76