LONDON — When Novak Djokovic walks back out on the grass at Wimbledon on Saturday, he’ll have plenty of work to do.

The three-time champion from Serbia trails Sam Querrey 7-6 (6), 6-1 in their third-round match, which was suspended by rain on No. 1 Court on Friday.

That’s right, the top-seeded Djokovic — the current owner of all four major titles — lost the first two sets.

“Sam has the game to pull off something like that with how he can serve and how he can hit his forehand and how he moves so well for someone his size,” said John Isner, an American who reached the third round on Friday and will be back on court on Saturday.

Djokovic surely isn’t out of the tournament just yet, but it’s the first time he has lost a set before the fourth round at a major in two years. It’s also the first time he has lost a set to an American at Wimbledon after five straight-set victories.

The 12-time major champion is halfway to a calendar-year Grand Slam, something no male player has accomplished since Rod Laver in 1969.

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The rain may have come at a good time for Djokovic on Friday, returning just after the second set ended to give him a break. But it has caused some havoc for the All England Club, which will schedule matches for the middle Sunday for only the fourth time in its 139-year history.

Several matches were suspended by rain on Friday, including some still in the second round. Normally, Friday and Saturday are for third-round matches.

The only other years the middle Sunday was added to the schedule were 1991, 1997 and 2004.