The ex-Manchester United youth striker suffered a hamstring problem in training on Sunday, which appears certain to rule him out of the trip to Fratton Park.

And with Jordan Henderson ruled out for a minimum of four to six weeks with an ankle injury he picked up in Saturday's 1-1 draw with Wigan and John Mensah (hamstring), Kieran Richardson (calf) and Anton Ferdinand (ankle) all still sidelined, manager Steve Bruce is without five key players for tonight's game against basement side Pompey.

He revealed: "Fraizer nicked his hamstring in training on Sunday and he is a big doubt - I don't think he'll be ready for tonight.

"It's a double setback because I was seriously tempted to use Fraizer's energy and pace on the right-wing after Jordan's injury - but that's an option which we're pretty certain we won't have.

"Our injury problems just seem to go from bad to worse at the moment, and it always seems to be our big players who are getting the knocks."

Bruce is still waiting to find out the full extent of the damage to Henderson's badly twisted ankle, which saw him stretchered off against Wigan in some distress.

The teenager will undergo a scan later this week when the swelling has gone down, and Bruce is keeping his fingers crossed that there are no broken bones.

But even a best-case scenario would see Henderson ruled out for a month, and in all likelihood it will be longer.

Bruce said: "Jordan will be out for a minimum of four to six weeks as far as we can tell.

"The swelling around his ankle should have gone down enough for him to have a scan on Thursday.

"We don't think it's broken - it seems to be just a bad twist.

"So we're hoping the scan will show no break and also that there is no serious ligament damage."

Ferdinand has been out of action since twisting his ankle in Sunderland's defeat at Fulham in early December, while Richardson aggravated his calf problem against Everton a fortnight ago, in only his second game back after a month on the sidelines with the injury.

But they are both nearing full fitness and, with a free weekend looming, could be back in contention by the time Sunderland's league campaign resumes at Arsenal a week on Saturday.

Bruce said: "We're hoping that Anton and Kieran will both be ready to start training again in the next week or so, but tonight will certainly come too soon for them."

Injury-prone Ghana international defender Mensah is also out with the hamstring injury picked up in the goalless draw with Stoke last week.

Sunderland have struggled with major injury problems over the last two months, with 10 first-teamers missing at one stage over Christmas, and that has coincided with their 11-game winless streak in the league.