Novak Djokovic and Roger Federer staged a couple of magical acts to set up another French Open semi-final at Roland Garros on Friday.

World number one Novak Djokovic saved four match points to outlast Jo-Wilfried Tsonga and return to the semi-finals.

The top-ranked Serbian breezed through the opening set to take it 6-1. But Tsonga, who was seeded fifth and playing in his first Roland Garros quarter-final, turned the tables. The Frenchman took the following two sets 7-5 after breaking Djokovic late in both.

The partisan home crowd was ecstatic by then, but the fans moaned with disappointment after Djokovic saved four match points to force a tie-break in the fourth set. The top seed went on to win that and the deciding set, 6-1.

The hard-fought victory in just over four hours means Djokovic remains on course for his fourth straight major crown, and could become the first man to hold all four Grand Slam titles since Rod Laver, in 1969.

Next up for Djokovic, is third seed and former champion Roger Federer, who also had to dig deep. The Swiss master faced the man he lost to in the final of the US Open in 2009, Juan Martin Del Potro.

The Argentinean took the opening two sets, 6-3, 7-6. But he crumbled and it was all Federer after that as the 30-year-old served out for a deserved five-set victory, 6-2, 6-0, 6-3.

So, Federer will next try to repeat his semi-final victory over Djokovic from last year, and says he is happy with the way he plays.