MADRID, May 7 (Xinhua) -- Novak Djokovic was made to dig deep in the first round of the Mutua Madrid Open on Monday.

The former world No. 1, who is only 10th seed in Madrid after a year battling against injury, faced a tough opening round tie against Japan's Kei Nishkori, who also fought against serious injury for a year.

The tough match saw Djokovic finally win 7-5, 6-4 under cloudy conditions in Madrid.

Djokovic now faces a possible tie against Kyle Edmund, the unexpected finalist in this year's Australian Open, in the next round.

The 15th seed Lucas Pouille followed 14th seed Tomas Berdych in crashing out of the first round when he was beaten by fellow countryman, Benoit Paire, 6-2, 6-3.

The 13th seed Diego Schwratzman progressed into the last 32 with a 6-1, 6-3 win over Adrian Mannarino

In the women's tournament, Maria Sharapova overcame a slow start before defeating Romanian Irina Begu 7-5, 6-1 to move into the last 16.

China's Shaui Zhang put up stiff resistance before eventually losing in three sets, 6-4, 4-6, 6-3 to France's Kristina Mladenovich.

The 7t seed Caroline Garcia had a 6-3, 7-5 victory against Petra Martic from the Czech Republic.