Carlos Alcaraz says for half the matches of the tennis season, players "don't feel that good" as the Spaniard secured a tour-leading 50th victory of 2025 at the Cincinnati Open.

The 22-year-old cruised past Serbian Hamad Medjedovic in straight sets 6-4, 6-4 in the third round to also claim his 13th consecutive Masters 1000 win.

Alcaraz is the first player since 24-time major champion Novak Djokovic, from 2013 to 2016, to reach 50 wins in four consecutive seasons.

The world number two will face Italian Luca Nardi in the fourth round on Wednesday.

"You have to think positively and just play your best tennis possible that day," said the five-time Grand Slam winner.

"I'm really happy that in really difficult matches I'm able to play my best tennis even though I'm not feeling the right way.

"I'm just happy and proud about it because it's something I'm working on."

Lucky loser Nardi, 22, led 16th seed Jakub Mensik 6-2, 2-1 when the Czech retired from their third-round match.

The first set between Medjedovic and Alcaraz was tight in the sweltering Ohio conditions, but the Spaniard got the break for 4-3 before sealing the opener.

Medjedovic then received treatment from the physio for neck pain.

Medjedovic, who is also 22, had a chance in the second set to take the lead at 3-3, but his attempt at two drop shots both hit the net. Alcaraz edged ahead to take a 4-3 advantage once again, and he wrapped up victory soon after.

Alcaraz has won seven ATP Masters 1000 trophies in his career, including the Monte Carlo and Rome titles this year.

He also successfully defended his French Open title by beating world number one Jannik Sinner in an extraordinary final at Roland Garros in June, before Italian Sinner defeated him in the Wimbledon final a month later.

Following the tournament in Cincinnati, Alcaraz heads to New York for the last Grand Slam of the campaign, the US Open, which begins on 24 August.

Players have been struggling with the heat during this week's tournament, with temperatures regularly exceeding 30C.

Francisco Comesana and Reilly Opelka both took medical timeouts during their third-round match, which was also interrupted for 45 minutes by rain.

Argentine Comesana won 6-7 (4-7) 6-4 7-5, saving three match points, but he needed medical attention in the second set, with a ball girl rushing to hand the 24-year-old a sick bag as he made his way gingerly back to his seat.

American Opelka, 27, also called for the doctor in the final set, complaining of dizziness and high blood pressure after being broken for 5-6.