Madrid, Rafael Nadal entered the round of 16 of the Madrid Open with a straight win over Serbian Miomir Kecmanovic 6-1, 7-6 (4) here on Wednesday.

The Spanish third seed raced away with the first set on his return to action after six weeks out with a rib injury, as his serve worked effectively, but he had to work much harder in the second set as Kecmanovic reacted well.

Nadal served for the set at 6-5 up only for Kecmanovic to break back and force a tie-break. The Spaniard last competed in March, when American Taylor Fritz ended his perfect start to the season in the Indian Wells final.

However, in a rain-disrupted clash against Kecmanovic, the World No. 4 played as if he had never been away, hitting with his explosive power as he recovered from failing to serve out the match at 6-5 in the second set to advance after one hour and 55 minutes.

"Every comeback is different. We had to put all circumstances together to analyse every single comeback, and today has been a very important match for me, playing at home on clay against a player that has been playing well for the past couple of months," Nadal said in his post-match press conference.

"So (if you) put everything together (it is) a very tough first round," Nadal added.

"I think I managed it very well. I played at a good level, so (I am) very pleased with the victory. I just try to stay humble to know things (are) not going to be perfect here and just moving forward with the right determination, to accept that I need to fight, I need to stay positive. I need to play with the right attitude, and take every single match that I'm able to win like a present to play another time here."

No. 5 seed Casper Ruud was the victim of an upset as Dusan Lajovic beat the Norwegian in three sets, 7-6 (7), 2-6, 6-4 to book a place in the round of 16, while ninth seed Cameron Norrie won another three-set match against big-serving John Isner, 6-4, 6-7(6), 6-4.

Roberto Bautista Agut, who was seeded 17th in Madrid, was knocked out by Britain's Daniel Evans, 6-3, 5-7, 7-6 (2) in a match that lasted just two minutes short of three hours.

In the women's quarterfinals, Ekaterina Alexandrova also booked her place in the semifinals thanks to a 6-4, 6-3 victory against Amanda Anisimova in an hour and a half.

Jill Teichmann moved into the last four with a 6-3, 6-4 victory against Anhelina Kalinina, while 12th seed Jessica Pegula completes the draw after knocking out Sara Sorribes Tormo 6-4, 6-2.