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9/16/2013 10:53 P.M. ET

A's know from experience not to celebrate too early

OAKLAND -- There are 13 games left in the regular season and the playoffs are in Oakland's sights with its largest division lead since 2006 -- a much different story compared to last season when it overtook the Rangers with a torrid comeback -- and the A's can mathematically win the division before the end of their last regular-season homestand of the year starting Monday and ending Sunday.

The A's improved to a season-high 27 games over .500 and extended their lead in the American League West to 6 1/2 games with their three-game sweep over the Rangers over the weekend. The team's magic number to win the AL West was at seven during Monday's opener with the Angels due to the Rangers' loss in Tampa Bay, and could fall to six with a win over the Halos.

"That's what I heard," reliever Sean Doolittle said, smiling wryly at the magic number talk.

But the A's reliever also made sure to toe the company line. Last year's comeback has provided a young team with perspective, and the A's would hate to be on the other side of the equation.

"It might be in the back of guys' minds, but I think we learned so many things last year," Doolittle said. "We got so much valuable experience from how things unfolded in September last year. I think every time you let yourself maybe look ahead a little bit, you remember what happened last year and how we want to stay in the driver's seat and everything like that. That's going to help us in so many different ways, and that's one of the ways that's kind of keeping us grounded and keeping us focused on what we have to do each day."

A's manager Bob Melvin continues to preach taking things day by day and taking the necessary steps to ensure they don't falter down the stretch.

"All those clichés, they tell us to say all the time," Doolittle said.

But, there's no denying that the A's are in an enviable position compared to last season.

"We have a bigger lead, but I'm not any more comfortable," Melvin said. "We have to finish this thing out. It's nice to win a series and gain some games, but until this thing's over, we have to play with the same intensity and the same focus we do every day.

"I learned that with nine games left and you're five down that you can win or lose it. No getting comfortable with the lead we have because there are 13 games left. We have to finish it out."

Parker, Cespedes return following scratches

OAKLAND -- Jarrod Parker and Yoenis Cespedes -- both late scratches in Sunday's series finale against the Rangers -- returned to the A's lineup for the first game of a three-game set against the Angels on Monday.

Parker missed his start due to illness and was replaced by Tommy Milone, but appears to be healthy enough to pitch Monday, when he looked to extend his franchise-best unbeaten start streak to 20 games. The rest of the A's starting rotation will remain the same and simply receive an extra day of rest.

"We had a pretty good idea the way Jarrod felt after the game yesterday that he was going to start today," A's manager Bob Melvin said before Monday's game. "It's kind of a blessing in disguise. … Everybody will benefit by getting pushed back a day."

Right shoulder soreness was the culprit of Cespedes' absence. He received an MRI in Oakland on Monday, but the results weren't made available by the start of Monday's game. The ailment affects Cespedes' throwing more than swinging, Melvin said, and as a result he hit fourth in the lineup as the designated hitter.

Cespedes injured the shoulder during the team's last homestand diving in left field, but his offensive output doesn't appear to have been hindered. He went 6-for-19 with nine RBIs on the A's six-game road trip and is batting .373 with three home runs and 13 RBIs in his last 13 games in September, eight of which have resulted in multihit performances.

"Whether it's a bruise or whatever is going on in there, it'll be a day-to-day proposition each and every day how he feels," Melvin said.

Cramps sideline Lowrie, who could return Tuesday

OAKLAND -- Shortstop Jed Lowrie exited Sunday's series finale against the Rangers after seven innings and was held from the A's lineup on Monday with a cramp in his right hamstring.

A's manager Bob Melvin deemed the decision precautionary, and both he and Lowrie have intentions of his return to the lineup on Tuesday.

"We got beat up a little bit in Texas. Those were three hard-fought games in tough conditions," Melvin said.

Lowrie said he first started to feel the cramp after Saturday's win at Rangers Ballpark in Arlington and told Melvin he'd play as long as he felt comfortable. Lowrie hit in the cage Monday and completed his normal pregame activities. Alberto Callaspo got the start at second base in his place.

"Dallas is known for causing cramps," Lowrie said. "I don't think it's out of the ordinary."

Worth noting

• University of California football coach Sonny Dykes thew out the ceremonial first pitch before Monday's game at O.co Coliseum. The former letterman on the Texas Tech baseball team met with A's manager Bob Melvin -- himself a former baseball player at Cal -- prior to the game.

"It sounds like he's just a true sports fan and being where he is now trying to see a little bit more of the community and the different teams here," Melvin said. "And once our season's over, I'd love to do the same, go out there and watch a football game or a basketball game or two."

• Beginning Thursday, the A's will use a walk-through metal detection system for fans entering O.co Coliseum.

The system will continue through any potential 2013 postseason games and for all future regular-season games. It also shares similarities with airport security. Fans are recommended to allow ample time for the new security procedure and to expect their bags to be searched and to empty their pockets of keys, cell phones and other items before walking through a metal detector.

Gates will open at 5:35 p.m. PT Thursday, 4:30 p.m. Friday, and 11:05 a.m. on both Saturday and Sunday.

• Dan and Tiffany Otero became proud parents of daughter Kinsley Lynn Otero Monday at 2:54 a.m. PT. She weighed 7 pounds, 4 ounces and was 21 inches long.

Jeff Kirshman is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.