Watford have been handed a fresh boost in their battle for Premier League survival with the return of Tom Cleverley from injury.
The former Manchester United and Everton midfielder, 30, has been sidelined for more than 100 days after limping out of Watford's goalless draw against Bournemouth in October.
But Cleverley is in line to make his comeback in the Hornets' crunch clash at Brighton on Saturday evening. Danny Welbeck returned from injury in Watford's 3-2 defeat at Everton last weekend.
"Tom Cleverley has trained with us continually now so he is in contention for Brighton," said Pearson. "We will assess Sarr tomorrow and make a decision on that.
"It is always a danger to put players at risk with soft-tissue injuries. With sprinters, and Ismaila is certainly a sprinter, there is more danger.
"With any injury like that you have to calculate the risk and decide whether the risk is worth taking. We have got 13 games left so it is prudent to make sure that when players like that are back, they stay back."
Since taking the job two months ago, Pearson has overseen a resurgence to give Watford a realistic chance of staying in the top flight, with the club having endured a dismal start to the campaign prior to his arrival.
A strong run of results temporarily lifted Watford out of the drop zone, but back-to-back defeats against Aston Villa and Everton leaves them 19th in the division, two points from safety. Brighton are three points ahead of Pearson's side in 15th.
"We have an opportunity at the weekend to get back to winning ways and that is what we will try to do," added Pearson.
"It is a very important game because there are a number of teams involved in the relegation battle and we are certainly one of them.
"It is important we put as much pressure on other teams around us, and we do that by getting our own results right.
"The realism of being involved in a relegation battle is that you have to get over setbacks pretty quickly."