Webb threw 32 pitches Wednesday.
The right-hander has not pitched in a game since the opener of the 2009 season because of shoulder problems. He underwent surgery last August and the Diamondbacks picked up the $8.5 million option for the final year of his contract in hopes he would be ready for the 2010 season.
Webb said he wanted to pitch in games now, but instead will have one more bullpen session Saturday. If all goes well, he said he could be ready to pitch an inning or two next Tuesday, when the Diamondbacks are in San Francisco.