By Martyn Herman

LONDON (Reuters) - World number one Novak Djokovic's brow may have furrowed slightly when he heard Andy Murray had teamed up again with former coach Ivan Lendl but he certainly was not surprised.

Djokovic has dominated Murray since losing to him in the 2013 Wimbledon final, but with Lendl back in the mix the threat level posed by the Briton may have been raised a notch or two.

"I don't think it's a surprising decision from Andy," Djokovic, who is halfway to a calendar grand slam after beating Murray in the Australian and French Open finals, said at the Boodles exhibition at Stoke Park near London on Wednesday.

"When Ivan was his coach before, Andy won a couple of grand slams and an Olympic gold medal, some of the best results of his career so I think it was a logical move for him to take.

"They're a good team so it's going to be interesting."

With eight-times grand slam champion Lendl at his side Murray beat Djokovic in the semi-finals of the 2012 Olympics, then repeated the trick a few weeks later to claim his first grand slam title at the U.S. Open.

When Murray again beat Djokovic to end Britain's 77-year wait for a men's Wimbledon winner a year later it seemed the Scot had the measure of the Serbian warrior.

Murray and Lendl split in March 2014 though, since when Djokovic has won 13 of their 15 meetings, most recently in the French Open final when Murray, who split with Amelie Mauresmo this year, subsided after a good start.

A few days later Murray re-hired Lendl and rolled on to a fifth title at Queen's Club -- marking him out as the man to end Djokovic's hunt for a rare calendar slam.

"I think the fact that his best success was with Ivan, it makes sense to give this another shot," Lendl's old adversary John McEnroe, now helping Canada's Milos Raonic, said in a conference call organized by ESPN.

"I think it makes people think if you get in someone's head in any way, whether that can make a difference, whether he makes a difference. He's done an excellent job in the past."

Djokovic, bidding for a 13th grand slam title, will take some stopping though as he currently holds all four majors -- the first man to do so since 1969.

The 29-year-old, who limbered for the defence of his Wimbledon title with a gentle work-out against Belgium's David Goffin on Wednesday and will face Nick Kyrgios on Thursday in a light-hearted match, is rested and primed for Wimbledon.

"We're moving on and it's back on grass starting from scratch now," Djokovic said.

"It's great that round the corner we have Wimbledon, back to back grand slams in less than a month and that will definitely make me focus and stay the journey."

(Editing by Pritha Sarkar)