French Open: Novak Djokovic pegged back by Juan Martin del Potro

Djokovic faces a battle if he is to extend his winning streak to 42 matches

Novak Djokovic will return to complete his third-round match at the French Open on Saturday with his six-month unbeaten run under serious threat from Juan Martin del Potro.

The powerful Argentine roared back into the contest to level at 3-6 6-3 when play was halted for the day at 9.12pm local time in Paris.

In a bizarre day, the must-see match of the first week fell victim to being scheduled last on the main Court Philippe Chatrier and, predictably, had to be moved as preceding matches ran into the evening.

After much confusion for spectators and presumably players alike, the decision was made to switch the contest to the vacant Court Suzanne Lenglen and play got under way at just after 7.30pm.

Djokovic, the world number two, brought into the tie a 41-match winning streak stretching back to last November, while Del Potro carried the menace of a brutal game that won him the 2009 US Open and had only been curtailed by injuries over the last year and a half.

Those lengthy absences explained why the Argentine is seeded only 25th and so had to face Djokovic at such an early stage, and the huge interest in the match was very obvious both inside and outside the stadium.

With play ending all around Roland Garros, the remaining spectators headed for Lenglen, and their boos flooded the arena as they were delayed entrance in the rush.

That was the unexpected soundtrack to the first set, dominated by Djokovic after an understandably scrappy opening couple of games, with the Serbian saving an early break point before finding the relentless accuracy that has seen off all-comers in 2011.

A single break in game four proved enough and it seemed possible that the second seed might have time to see out the match in straight sets and give himself a day off.

Del Potro had other ideas, though, increasingly winding up the huge forehand that flattened Federer at Flushing Meadows two years ago, and a Djokovic double fault saw him break at 3-1 in the second.

The crowd, which was now largely inside the stadium rather than queuing outside, was thrilled by the tussle and huge roars greeted Del Potro's recovery from 15-40 when serving for the set, four huge serves hauling him level.

An epic battle appeared to be unfolding but, with darkness descending and the scores level, there was only one decision that could be made and play was stopped for the day, to the predictable chorus of boos on a bad day for tournament organisers.

The pair will resume in Saturday's third match on Court Suzanne Lenglen at around 1400 BST, immediately after Andy Murray's clash with Michael Berrer, both matches being shown live on the BBC website for UK users.