OAKLAND -- Lance Niekro was confident his ailing right shoulder was ready for action after his range of motion was good on Friday, but manager Felipe Alou noted Saturday that the first baseman might require a stint on the disabled list.

Nothing like a quick 180-degree emotional state.

"I definitely thought it would be better than it was," said Niekro, after attempting to swing and throw minutes after optimism prevailed. "It was really difficult. It's different once you get into a game mode instead of hitting off a tee.

"Once I started speeding things up, it was hurting pretty good," continued Niekro, who injured the shoulder last Sunday while diving for a ball on a bunt against the Los Angeles Dodgers at AT&T Park. "And the throwing part wasn't anything special."

Alou had toyed with the idea of starting or pinch-hitting Niekro soon, but with the shoulder aching after a week off, the team didn't want to chance a major setback.

"I waited a little bit before I wrote the lineup, but I didn't hear anything about him," said the manager. "We have considered [putting him on the DL], but not seriously. But it has been considered."

Niekro's career has been dogged by a variety of injuries, and earlier this season he was bothered by shinsplints. He stayed off the DL in 2005, but also dealt with nagging problems in the second half.

"If you asked me the night I [got injured], I would have said I'd be good in a day or two," said the 27-year-old Niekro. "So it's definitely surprising that it's going like it is."

Veteran Mark Sweeney has started in Niekro's spot this week and is batting .300 on the roadtrip with three RBIs. He's 3-for-6 the past two games.

Cain improved: Rookie starter Matt Cain makes his first start since May 10 on Sunday vs. the A's, and the right-hander feels skipping a turn helped him mentally and physically after a rough early season.

Cain, 1-5 with a 6.69 ERA over eight games, seemed totally out of sync at times and really struggled in his first two May contests, going only 9 1/3 innings and giving up 13 earned runs for a 12.54 ERA.

Mechanics seemed the main problem, but the 21-year-old Cain said the mental side was the toughest issue to overcome.

"Some of it was just for me to calm down a little bit," said Cain, whose two innings of scoreless relief on Wednesday in Houston showed immediate improvement.

"They liked that I'm energetic, but I can't be too hyper out there," cotinued the pitcher. "You start rushing through your mechanics, so the big thing was to take a step back and think about what's going on."

Cain's famous stuff -- that screeching fastball -- was there, but the location was off due to minor mechanical problems and because he was too anxious to be perfect.

"Pitchers need to set the time of the game -- they're working quick and keeping it going, but you have to slow it down a little bit just to keep the players off-balance a little bit," said Cain.

Ellison gets start: Fifth outfielder Jason Ellison was a no-show in the Giants clubhouse pregame Saturday -- for good reason. Ellison was hitting in the batting cage, preparing for his first start of the season.

Ellison has played in 34 games, mostly logging late-inning appearances as a pinch-runner and pinch-hitter. He's batting .267 and was hitless in his last four at-bats heading into Saturday's contest.

Coming up: Cain resumes rotation duties Sunday against Oakland at McAfee Coliseum in a 1:05 p.m. PT Interleague contest. The Athletics will feature right-hander Joe Blanton (4-4, 5.84 ERA).