But with Ireland international Tomas O'Leary ruled out long-term after back surgery, Phibbs made the switch to Irish at the end of December and was handed his first Aviva Premiership start of the season in their crucial 18-12 win at Gloucester Rugby at the beginning of January.
That result ended a run of six straight Aviva Premiership defeats, and with a tough home clash against Saracens and a vital trip to Bath Rugby coming up next month, Phibbs insists he is thriving on the pressure.
"For me it's a great way to challenge myself. We're battling to stay alive - in a way it's almost like playing a cup final each week," said Phibbs.
"I've never been involved in a relegation battle like this. It's a great opportunity to be able to help the club get out of this.
"London Irish is a club with a rich history and no one here wants to be down in the Championship.
"The win against Gloucester was a fitting way to start for the club. Any win in the Aviva Premiership is going to be a good win for us now, especially away from home.
"I made the move to come to this club to play a bit more rugby. It was disappointing at Leicester Tigers but they have a world-class player in my position in Ben Youngs.
"I just wanted more game time. It didn't work out but I still made inroads with my physical ability there."
Over the last fortnight Irish ended their Amlin Challenge Cup campaign with a 20-14 win at Montois and a 17-7 victory at home to Begles Bordeaux, though Phibbs played no part in either.
The Exiles' attentions now turn to the visit of Worcester Warriors and a trip to Cardiff Blues in the LV= Cup.
And Phibbs is hoping to get another chance to shake off the rust before Irish return to Aviva Premiership at home to Saracens on February 9.
"I want to play myself into a bit of form. I haven't played too many games this season and I'm almost lacking a bit of game time," said Phibbs.
"I was thrown right in at the beginning but now I've had a bit of time to get to know the structure of the club.
"But I want to get back out on the field and sharpen up my decision making and my match fitness.
"You can train as much as you want but it's never the same as actually playing a game. Hopefully I can get a bit more game time in the LV= Cup.
"Ideally the Aviva Premiership is what we want to stay in the most and it's our main focus.
"But to stay in the running for the LV= Cup is good for the supporters and the players as well."
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