Santana and Saunders will be pushed back a day, which means Saunders will work the opener of a big three-game series against the Rangers starting on Friday night at Angel Stadium.
"We targeted the eighth" for an appearance by a fifth starter "three weeks ago," Scioscia said. "We're going to spot somebody in there in Chicago after Lackey to let some guys get a little extra breathing room, freshen some guys up, hopefully.
"It's not going to hurt to do this. We're seeing Joe's stuff pick up, Ervin's stuff pick up. Any pitcher at this time of the season can use a little extra time. I think [Jered] Weaver will benefit."
Weaver, Sunday's starter against the Twins, figures to make his next appearance on Saturday at home against the Rangers, with Lackey, the ace, dealing in Sunday's series finale on his regular rest.
Weaver admitted before his outing in the Angels' final appearance at the Metrodome -- their new stadium is planned to be open for business next April -- that he has been experiencing what might be a "little dead arm" stage.
O'Sullivan, Matt Palmer and Shane Loux have handled the No. 5 spot in the rotation since Dustin Moseley departed after three starts with an right arm ailment complicated by a nerve issue and Kelvim Escobar's right shoulder became inflamed after one excellent start in Detroit on June 6.
O'Sullivan is 3-0 in five starts with a 3.72 ERA. The Angels have won all five games, and the big right-hander from the San Diego area didn't hurt himself with his masterwork against Sacramento, facing one batter over the minimum in his no-hitter.
"He was 1-2 [in the count] against the guy who walked leading off the seventh," said Bobby Wilson, who caught O'Sullivan that night. "He missed with a couple of close pitches and then walked him.
"Sean was putting his fastball wherever he wanted it. Out of his  pitches in that game, I'd say 80 percent were fastballs. He really had it working, so we stuck with it."
Wilson was as thrilled as O'Sullivan with that July 28 gem in Sacramento. The 21-year-old El Cajon, Calif., native struck out seven hitters.
"It's the first no-hitter I've ever caught -- anywhere," Wilson said.
It featured superb defensive plays by Brad Coon in center field and second baseman Sean Rodriguez, who delivered the final out. Rodriguez makes his second straight start in left field for the Angels on Sunday after delivering two hits and two fine catches on Saturday.
"Sean was dealing that night," Rodriguez said. "He really wants to get back up here."
It looks as if he'll get his wish on Wednesday in Chicago.