Clarke has yet to feature for Leeds since falling ill on the bench during the second half of United's 1-1 draw at Middlesbrough on February 9.
The teen was transferred to James Cook University Hospital having received treatment and oxygen from paramedics in the away dug-out and the winger has been carefully integrated back into United's plans since.
Clarke then came through 80 minutes playing for United's under-23s against Charlton Athletic on Monday, after which Bielsa was considering whether or not to bring Clarke back into the first team fold for the weekend derby against the Blades.
But speaking at Thursday's pre-Sheffield United press conference, Bielsa said he would first see how Clarke fares in another outing for United's under-23s tonight against Fulham in the Premier League Cup (kick-off 7pm at Nethermoor Park).
"He's going to play today," said Bielsa of Clarke.
"We will see how he assimilates the game and I will take a decision after that."
Bielsa also provided positive updates on striker Kemar Roofe and midfielder Adam Forshaw who are now United's only two injuries.
"They are evolving," said Bielsa.
"They are in the final stage of their recovery but I can't tell you any more than that."