Bathurst champion Greg Murphy will take his place on the grid for this weekend’s L&H Phillip Island 500.

Murphy, who is recovering from recent back surgery, made the call to race in Sunday’s Bathurst warm-up after practice late this afternoon.

"I think I'll stick it out, the back’s no problem at all and the leg situation with the nerve doesn’t feel any different to what it did this morning [before I jumped into the car] so I think it will be alright," Murphy said.

The four-time Bathurst winner underwent surgery just over two weeks ago to fix a bulged disc in his back suffered when he was on a family holiday in Fiji recently.

Murphy’s decision to race means Kiwi Daniel Gaunt, who tested with the team last week and was in the Castrol team garage today, misses out on a drive this weekend.

Rookie Tim Blanchard will co-drive with Murphy. The pair set the 21st best time in today’s practice.

Team BOC drivers Jason Richards and Andy Jones ran through a series of set-up changes to their car and, despite Phillip Island’s changing weather conditions, reported good progress.

The pair ended the day 16th fastest but both are confident of big improvements tomorrow, when they will use their first set of fresh tyres.

The team has another two practice sessions tomorrow morning before qualifying for the race begins at 11.30pm.

Richards looked ahead to Saturday's qualifying, but said there were still improvements to be made.

"I think we're going OK. I didn’t really like it on the used tyres and we’re still tuning the car; it’s definitely not 100%. We’re trying a lot of new things from what we found at the test but it’s hard with the limited dry running to really assess them. We only just got into it right at the end," Richards said.

"Andy went extremely well; he had very strong pace even on the used tyres and I think our combination will be really good."