Rovers’ influential captain went off at half time against Ipswich Town on Tuesday night after taking a whack on the ankle.
The 33-year-old has formed a useful midfield partnership with Matt Smith in recent games and hopes to be fit enough to face Pompey.
However, Ethan Galbraith has not recovered from a calf problem and is likely to miss next Tuesday’s trip to Lincoln City as well as this weekend.
“Tommy’s got a bit of a swollen ankle," said Rovers boss Gary McSheffrey. “It’s a bit black and blue with a gash on it, so obviously he didn’t train but he’s icing it around the clock and doing as much as he can to be available.
"We’ll just have to monitor that until the last minute.
"I don’t feel there’s too much damage to the ankle in terms of it being the ligament but it’s really swollen from the impact injury he took on it. There’s a cut on it and a lot of bruising. He’s not ruled himself out.”
“Ethan’s back at Manchester United for a few days and we’ll touch base and reassess it at the beginning of next week but I wouldn’t say he’d be available for the next couple.”
Meanwhile, midfielder Ben Close has been ruled out for the rest of the season after undergoing knee surgery.
John Bostock, Tom Anderson, Jon Taylor, Cameron John and Fejiri Okenabirhie remain sidelined.