Cubs manager Mike Quade said before a 6-1 win that Marmol, who was given two days off to try to fix his mechanics, was available if pitching coach Mark Riggins and bullpen coach Lester Strode felt the right-hander was ready.
Would Marmol be used in a save situation?
"It would depend on the situation and I'm not sure I've settled on that yet," Quade said.
Marmol entered in the ninth with a five-run lead Monday, so it wasn't a save situation, but he made it a little more difficult.
Marmol struck out Ryan Howard to start the inning, then got Raul Ibanez to ground out. But he walked the next two batters, and Riggins went to the mound.
"I'm glad he came out there," Marmol said. "I couldn't breathe."
That's because of the heat and humidity, which had knocked Phillies starter Roy Halladay out after four-plus innings.
Marmol struck out John Mayberry Jr. to end the game,and turn the boos to cheers.
"When I go out there, I don't worry about the fans," said Marmol, who has heard his share of jeers. "I try to get three outs. I don't want them to boo me."
The right-hander said he felt better on the mound, despite the walks.
"I don't worry about the walks," he said.
First baseman Carlos Pena also gave Marmol a pep talk.
"I thought today was great because it presented a challenge for him," Pena said. "He got two quick outs, then walked the next two batters and the mental monster appears.
"We came to the mound to remind him he doesn't have to carry the last outings he's had that he hasn't liked, and he doesn't have to strike out three people at the same time," Pena said. "All that matters is this pitch that he's throwing right here and that's good enough.
"He slayed the dragon at the end there," Pena said. "He stayed focused and came out with the pitch at the end."
In his last seven games prior to Monday's game, Marmol had given up eight runs on five hits and seven walks over 4 1/3 innings and had not struck out a batter since July 3.
"I would like him to get the most out of his downtime and he has so far," Quade said. "If they feel good about it, we'll be good to go."
Marmol said he had a better feel for his slider and fastball and learned a lot in the last two days. Bottom line, only he can fix his mechanics.
"I have to listen to myself," he said. "I got to be me out there."