Mark Philippoussis in awkward scenes amid sad Stefanos Tsitsipas blow at United Cup

Mark Philippoussis has landed on his feet after being dumped from Stefanos Tsitsipas' coaching team for a second time, scoring a job in commentary for Channel 9 during the summer of tennis. The Aussie great has worked on and off with Tsitsipas over the last few years, but has found himself on the outer again after the Greek's poor showing at the US Open.

The World No.6 has never made it past the third round at Flushing Meadows, and the sorry situation continued in August with a shock five-set loss against World No.128 Dominic Stricker in the second round. It came to light in the aftermath of his exit that Tsitsipas had once again parted ways with Philipppoussis, after the pair also split in June before getting back together.

LOVELY: Petra Kvitova news delights tennis fans amid Naomi Osaka return

'DIDN'T SAY THAT': Rafa Nadal's shock announcement amid tennis return

Tsitsipas brought Philippoussis back in to be his head coach in early August - replacing his father Apostolos. Speaking at the Toronto Masters, Tsitsipas explained: "My father right now, I gave him some time off. He hasn't had time off since I'm 12 years old. I think for him, it's very healthy to take some time away from the court and feel refreshed again."

But Tsitsipas was quick to bring his father back and send Philippoussis packing after the US Open. Apostolos is back working with his son at the United Cup in Sydney as the Greek star prepares for the Australian Open.

And it's the same tournament that Philippoussis is working at for Channel 9. In awkward scenes, the Aussie great even conducted a court-side interview with Tsitsipas during Greece's tie against Chile on Tuesday. Despite the awkwardness, fans were happy to see Philippoussis on their screens.

Stefanos Tsitsipas out of United Cup match with back issue

It was during the interview that Tsitsipas revealed he's dealing with a lower back complaint. It later came to light that the World No.6 had withdrawn from the singles rubber against Nicolás Jarry, with Stefanos Sakellaridis taking Tsitsipas' place.

" There are a few chances I might not play, and there are a few chances I might, so I'm kind of 50-50 so far," Tsitsipas said. "We will wait and see."

Maria Sakkari had earlier gotten Greece's United Cup campaign off to a flying start with a straight-sets victory over Daniela Seguel. The World No.8 took just 26 minutes to wrap up the first set and kept her foot on the gas to claim a 6-0 6-1 victory.

"I don't feel match sharp but I feel good," Sakkari said. "I'm very happy to have given my team the first point and I have full belief in the team so I'm super excited for what's coming."

Alex de Minaur stars as Australia advance to United Cup quarters

On Monday night, Australia advanced to the quarter-finals after Alex de Minaur beat Taylor Fritz to help his side eliminate the USA. De Minaur kicked off the tie with a dominant 6-4 6-2 win over World No.10 Fritz, in a huge statement before the Australian Open.

Ajla Tomljanovic then lost 7-6 (8-6) 6-3 to World No.5 Jessica Pegula, meaning it all came down to the deciding mixed doubles rubber. Matt Ebden and Storm Sanders knew they needed to win in straight sets in order for Australia to top the group, which also featured Great Britain. And they did exactly that, defeating Pegula and Rajeev Ram 6-3 6-1 to knock the defending champions out in the group stage.

"They played fantastic, it was great," Aussie captain Lleyton Hewitt said. "I'm very proud. It was backs against the wall after our first match. They left everything out there. It bodes well for Wednesday night."

Sign up to our newsletter and score the biggest sport stories of the week.