British number three Cameron Norrie is through to the Delray Beach Open semi-finals after a 6-0 3-6 6-4 win over Frances Tiafoe.

Victory in Florida set up a last-four tie with Sebastian Korda, who beat second seed and fellow American John Isner in the quarter-finals.

Isner then announced he will not play in February's Australian Open.

The world number 25 does not want to be away from his young family for an extended period, given they cannot travel with him as they usually would because of Covid-19 restrictions.

"At this stage of my career and in my life, I always had visions of being able to travel with my family," said the 35-year-old.

"Of course, that wouldn't be the case for Australia this year. Understandably so, I get it. It really was just a situation where I didn't want to be away from my family for that long. I decided to stay home."

Elsewhere at the Delray Beach Open, world number 789 Christian Harrison's run continues after he reached his first ATP Tour semi-final.

The 26-year-old American defeated Italian Gianluca Mager 7-6 (7-2) 6-4 and will play fourth seed Hubert Hurkacz in the last four.

Harrison, who has had eight surgeries, had just two tour-level singles wins before this week and is also through to the doubles semi-finals alongside older brother Ryan.

"It feels pretty amazing," Harrison said. "I'm just happy that I have everyone here, all my friends and family around that are here to support, especially here in Delray being so close to home."

Harrison has been fined $3,000 (£2,212) by the ATP after refusing to take part in a mandatory on-court interview following his second round win over top seed Cristian Garin on Saturday because he was required to wear a mask.

He wore a mask for a subsequent on-court interview and later said he was "given the impression" they were optional.

"It's not healthy to wear a mask in the hot sun for more time than absolutely necessary after a tough match. I was given the impression it was optional. I wasn't told I would be fined," he said on Instagram.

"I was required to do a sit-down interview after the match with the same person which I agreed to and I did not have to wear a mask for it. It's not about safety to wear mask for TV to talk to a microphone with no-one around.

"I don't support masking people for the sake of it for TV."