Roberts made his first Premier League start since mid-October in an unaccustomed central striker’s role in the continued absence of Patrick Bamford.
The Wales international had a big impact off the bench in last week’s goalless draw at Brighton and followed it up with another performance which clearly impressed his manager.
Bielsa said: “He was very important. He didn’t stop fighting, ever. He kept our team alive, present. I didn’t imagine he could run as much as he did throughout the 90 minutes.”
Roberts has struggled to win a regular starting place throughout his time at Elland Road.
When asked if he had produced his best Premier League display yet against Palace, Bielsa added: “It’s always difficult to answer those questions because you don’t have all the other games in mind, it’s a performance that shows he is an option.”
Raphinha converted a stoppage-time penalty to clinch Leeds’ third league win of the season after Liam Cooper’s header had struck Palace defender Marc Guehi on the hand.
Victory was crucial for Leeds in their fight to climb clear of relegation trouble.
They next face Brentford at Elland Road on Sunday before a daunting Christmas schedule, which includes games against Chelsea, Manchester City, Arsenal and Liverpool.
Midfielder Adam Forshaw was another stand-out performer for Bielsa’s side against Palace in just his fourth league start since overcoming a career-threatening hip injury.
“Very, very impressed with him,” Bielsa said. “To be fair and sincere, I didn’t expect him to come back to who he was before.
“And to have achieved it in a succession of games, he deserves to be valued by those who helped him get healthy and for himself.
“I myself don’t include myself in that contribution because I never expected him to come back in this way.”
Palace boss Patrick Vieira said afterwards that his side had been the more impressive and, having created most scoring chances, defeat was hard to take.
Vieira had no complaints about referee Kevin Friend’s penalty decision – he pointed to the spot after watching a replay on the pitch-side monitor – and refused to blame Guehi for his side’s cruel defeat.
“I don’t need to speak to him (Guehi) about it,” Vieira said. “I think he’s frustrated and he will learn from that.
“He’s a player who needs to keep believing in himself and learning. You have to go through those situations.
“I’m really pleased with the game he had tonight. I think Marc is growing as a player and as a person and I’ve been really pleased with his leadership in the squad since he arrived.”
Palace, who slipped to back-to-back defeats for the first time under Vieira, play at Manchester United on Sunday.