The Rebels take on the Sunwolves in Tokyo on Saturday in a must-win match with just four rounds left to seal a finals berth.
Mafi played two seasons with the Rebels and was crowned Australian Super Rugby player of the year before leaving in disgrace after allegedly assaulting teammate Lopeti Timani in a drunken post-match incident.
During his time, his barnstorming carries made the backrower a crowd favourite in Melbourne and Philip said that was something the Rebels needed to shut down.
“I think Mafi can be a big source of energy for a team,” Philip said.
“He’s obviously a really good ball carrier, so he’s probably someone I’ll single out for myself to make sure that every time he gets the ball, to focus on hitting him early and probably stamp him out of the game pretty early as well.
“If we can stop Mafi, I think that could be a bit of an entry point to getting into their game and stopping that go-forward he brings.”
Despite the circumstances of Mafi’s departure Philip said there was no ill will from the Rebels toward the Japanese international.
Timani has also since left the club.
“We’ll attack him just because he’s a good rugby player, not for anything else,” Philip said.
“He’s still got a lot of friends here in this group – he was a good guy for the most time he was here, he just made one mistake and we can’t hold everything against him for that one mistake.”
Hopeful of adding to his three Test caps ahead of World Cup selection Philip 25-year-old wants to bring more aggression to his game.
He said he always enjoyed watching the likes of hard nut South African lock Bakkies Botha.
“It’s just something that if I was looking at my career, that’s something I would like to see my identity as,” Philip said.
The Rebels currently trail the conference-leading Brumbies by a point so victory over the Sunwolves, who have just two wins for the season, is crucial.
“We’ve acknowledged the situation we’re in now, the Brumbies are one point ahead of us, so every game counts.
“We’ve set our goal as a team – we want to make finals and I think we would be disappointed as a group if we don’t make finals – and I’ll definitely be disappointed.”
In other news:
Sign up to our mailing list here and we’ll keep you up to the minute with weekly updates from the world of rugby.