LONDON, July 4 (Xinhua) -- Defending champion Carlos Alcaraz remained on course for a third straight Wimbledon title after defeating Jan-Lennard Struff in the third round on Friday.

The second-seeded Spaniard secured a 6-1, 3-6, 6-3, 6-4 victory, converting five of 12 break points. He excelled on second returns, winning 34 of 55 points - a key factor in his win.

"I think I returned pretty well. It just puts so much pressure on his serve. I think it was the key today," the 22-year-old said.

Alcaraz will next take on 14th seed Andrey Rublev, who eased past Adrian Mannarino 7-5, 6-2, 6-3.

The two-time champion anticipates a tough match against the aggressive Russian.

"He's a really powerful player. I think he plays really well on grass because he always loves to be aggressive," he said.

"When he finds his forehand, I think he likes to move his opponent from side to side. It's going to be really difficult because on grass, the movement is the most difficult thing to do," he added.

Meanwhile, fifth-seeded American Taylor Fritz advanced with a 6-4, 6-3, 6-7 (5), 6-1 win over Alejandro Davidovich Fokina and will meet Australia's Jordan Thompson in the next round. Thompson defeated Italy's Luciano Darderi 6-4, 6-4, 3-6, 6-3.

In the women's draw, top seed Aryna Sabalenka overcame a spirited challenge from Britain's Emma Raducanu, winning 7-6 (6), 6-4.

Trailing 4-1 in the second set, Sabalenka rallied to claim five consecutive games.

"Emma played such incredible tennis and she pushed me really hard to get this win," said Sabalenka.

"I had to fight for every point to get this win," the 27-year-old Belarusian added.

Elsewhere, Australian Open champion Madison Keys fell to 37-year-old German Laura Siegemund 6-3, 6-3, while former world No. 1 Naomi Osaka squandered a set lead to lose 3-6, 6-4, 6-4 to Anastasia Pavlyuchenkova.