Paris - Top seed Novak Djokovic reached the French Open quarter-finals on Monday with a 4-6, 6-3, 6-4, 6-4 win over German 16th seed Philipp Kohlschreiber.
Djokovic will face Germany's Tommy Haas for a place in the semi-finals.
"It's very difficult to play against Philipp as he is a specialist on clay. After the first set, I played well so I am happy," said the world number one.
"It was windy, but the conditions were the same for both of us. I just had to adjust."
On facing Haas, the third oldest man to make the last eight, the Serb said: "I have a lot of respect for Tommy. He is playing well."
Djokovic, the runner-up to seven-time champion Rafael Nadal last year, needs a French Open title to complete a career Grand Slam.
The last time he failed to reach the last-eight of a major was in Paris in 2009 when he lost in the fourth round to Monday's opponent.
Kohlschreiber stunned the Serb by breaking in the fifth game on his way to taking the first set.
Djokovic was warned for taking too long between points in the seventh game of the second set, but he still went on to level the tie.
A break in the third game of the third set and the fifth game of the fourth put him on the verge of victory.
The German saved a match point when Djokovic served for the tie in the eighth game and broke for 3-5.
But Djokovic hit back in the 10th game to take victory and reach his 16th consecutive Grand Slam quarter-final.
Kohlschreiber paid a heavy price for being able to convert just two of his 13 break points.
French Open fourth round results (x denotes seeded player):
Men:
Fourth round:
Novak Djokovic (SRB x1) bt Philipp Kohlschreiber (GER x16) 4-6, 6-3, 6-4, 6-4
Tommy Haas (GER x12) bt Mikhail Youzhny (RUS x29) 6-1, 6-1, 6-3
Rafael Nadal (ESP x3) bt Kei Nishikori (JPN x13) 6-4, 6-1, 6-3
Stanislas Wawrinka (SUI x9) bt Richard Gasquet (FRA x7) 6-7 (5/7), 4-6, 6-4, 7-5, 8-6
Women:
Fourth round:
Maria Kirilenko (RUS x12) bt Bethanie Mattek-Sands (USA) 7-5, 6-4
Victoria Azarenka (BLR x3) bt Francesca Schiavone (ITA) 6-3, 6-0
Maria Sharapova (RUS x2) bt Sloane Stephens (USA x17) 6-4, 6-3
Jelena Jankovic (SRB x18) bt Jamie Hampton (USA) 6-0, 6-2