Madrid: Novak Djokovic overcame stiff resistance from Feliciano Lopez to book his place in the quarter-finals of Madrid Masters with a 6-4, 7-5 win on Thursday.

Djokovic had battled back from 3-0 down in the deciding set in his opening match against Nicolas Almagro in the Spanish capital on Wednesday.

And, although not pushed that far by Lopez, the Serb is still struggling to rekindle the form that saw him hold all four Grand Slams just under a year ago.

Djokovic was, though, dominant on serve throughout, facing only one break point in the opening game of the second set.

And the 12-time Grand Slam champion applied just enough pressure at the right time to break Lopez’s serve in the final game of both sets.

Djokovic faces a much tougher test on Friday against world No. 8 Kei Nishikori, who earlier swept aside David Ferrer 6-4, 6-3.

In the women’s Madrid Open, third seed Simona Halep remains on course to defend her title as she thrashed American Coco Vandeweghe 6-1, 6-1.

Halep faces Latvian Anastasija Sevastova in Friday’s semi-finals after the world No. 22 saw off Kiki Bertens 6-3, 6-3.

Meanwhile, Roger Federer is set to make his 15th appearance at Halle’s ATP tournament next month in his bid to win the title for the ninth time, organisers said on Thursday.

The 18-time Grand Slam winner, currently ranked fourth in the world, has confirmed he will play at the grass-court tournament from June 17-25 — traditionally a warm-up for Wimbledon, which starts on July 3.

It will be the 15th-time Swiss tennis legend Federer, 36, has played in Halle which he won for the eighth time in 2015.

“We are looking forward to Roger’s return,” said tournament director Ralf Weber.

“He has finally helped bring the tournament into a new dimension and made it even more popular worldwide.”

Along with Federer, eight of the top 20 in the world will be in Halle including last year’s beaten finalist Alexander Zverev, 20, who won the Munich clay-court ATP tournament last Sunday.