Cameron Munster trained strongly with Melbourne on Monday but has one final hurdle to overcome to play in the NRL blockbuster against Brisbane at AAMI Park on Thursday night.
The Storm five-eighth has been a thorn in the Broncos' side for the best part of a decade and is one of the key reasons Melbourne have not lost to their fierce rivals at home since 2016.
Munster, who hasn't played this year due to an off-season groin injury, completed training without a problem on Monday.
But it is not whether he can run that is the issue regarding his playing return. It is how he recovers from training.
Coach Craig Bellamy has stated previously the injury has been a day-by-day proposition as far as Munster's recovery is concerned, and nothing has changed.
"We will see how he pulls up tomorrow from training today. That is the key," Storm general manager of football Frank Ponissi told AAP on Monday.
"Today is the hardest he has gone. Whether he plays or he needs another week, we will just have to wait and see.
"He is not a certainty. All along we have said he has to get back to full training.
"He has been running for a while. It is just how he pulls up from the runs afterwards."
The Storm will welcome back prop Christian Welch from concussion, while star half Jahrome Hughes returns from suspension.
Melbourne missed both in the 14-12 loss to Newcastle in round three before they had the bye.
"Welchy is back from concussion," Ponissi said.
"He passed that the with flying colours and Jahrome Hughes is back from suspension. They are two certainties."