What is a walkover in tennis? Rafael Nadal gets a walkover into the semifinals of the Melbourne Summer Set

Rafael Nadal strolled into the semifinals of the Melbourne Summer Set on Friday without having to hit a ball in his quarterfinal match.

The World No. 9 was scheduled to play against Tallon Griekspoor, but the Dutchman pulled out at the last minute due to a foot injury. The World No. 65 took to Twitter to announce the unfortunate news and said he hopes to get back to full fitness before the 2022 Australian Open begins on January 17.

"These are the matches you play for. Sad to pull out with a foot injury.. Trying everything to be healthy for AO in 10 days time!" Griekspoor tweeted.

Courtesy of the walkover, Rafael Nadal will now lock horns with World No. 95 Emil Ruusuvuori for a place in the final. Nadal is seeded No. 1 at the tournament and received a bye in the first-round as well, meaning that he has reached the penultimate stage of the ATP 250 event with just one win under his belt.

The Spaniard will hope to get some much-needed game time in his remaining matches before heading into the 2022 Australian Open. Nadal will have a shot at winning his 21st Grand Slam at the tournament, taking him one clear of Roger Federer and Novak Djokovic. Federer will miss the the Grand Slam due to injury, while Djokovic's participation is looking increasingly unlikely.

In the doubles category of the Melbourne tournament, Nadal and his partner Jaume Munar withdrew from their second round match against Andrey Golubev and Franko Skugor.

What is a walkover in tennis?

Roger Federer withdrew from his match against Matteo Berrettini at the 2021 French Open

A walkover in tennis happens when an opponent pulls out of a match even before it has begun. If a player retires midway through a match due to injury or other reasons, it is not considered a walkover but a retirement.

The important distinction between a walkover and a retirement is that walkovers do not count towards a player's win/loss record, while retirements do.

For example, Roger Federer forfeited his Round of 16 match against Matteo Berrettini at Roland Garros in 2021. Despite that, Federer leads the head-to-head against the Italian 2-0 since he pulled out before the match began.

Serena Williams retired from her first-round match at Wimbledon last year against Aliaksandra Sasnovich due to a hamstring injury, with the score at 3-3. However, Sasnovich now holds a 1-0 lead in her head-to-head against the American.

Tangentially, defaults also count towards a player's win/loss record. When Novak Djokovic was defaulted at the 2020 US Open for accidentally hitting a line judge, the win was awarded to Pablo Carreno Busta.