Powerful Argentine Juan Martin del Potro was due to return last night to continue his impressive challenge to hot favourite Novak Djokovic at the French Open in Paris.

Djokovic and del Potro were set to resume what looked likely to be a thrilling encounter at one set apiece after bad light stopped play the previous evening. Djokovic's six-month unbeaten run was under serious threat from del Potro.

The tall 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 after a bizarre day.

Unsurprisingly, the most important 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.

But the move meant many spectators were either caught out or locked out and their boos and jeering could be heard on court - so much so that a miffed Djokovic complained to the umpire.

Djokovic 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 but which had 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.

The huge interest in the match was obvious both inside and outside the stadium. With play ending all around Roland Garros, the remaining spectators headed for Lenglen, and their protests 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.

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 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. The pair were due to resume at around 2am today.

- Agencies