But if Lopez has anything to say about it, his playing time at first base will be limited to the final two weeks of this season.
"I don't have a problem with it, but next year I don't want to move my position," Lopez said. "I don't want to play first base. I want to help the team right now, but I don't want to move my position to first base."
Manager Jim Riggleman explained the surprise move prior to the game, saying it is something that has been discussed within the organization for more than a week, and had more to do with getting a closer look at rookie second baseman Luis Valbuena during the final two weeks of the season than finding a new home for Lopez.
"I told him that we want to have his bat in there, but we want to watch this kid [Valbuena] play second base," Riggleman said. "He is a second baseman, not a shortstop, not a third baseman and not a left fielder. He plays second and that's it. Jose is good with it, and said if that's what the team needs him to do, that's what he will do. He has been working out over there [first base] for the past two or three days."
That isn't much practice time, but the Mariners believe Lopez can make the switch without much difficulty, but if he struggles, don't blame him.
"It's one of those things that if he struggles over there, it's on me," Riggleman said. "The thing you don't want to do is embarrass a player by having him look awkward somewhere. If that were to happen, it would be my responsibility. It wouldn't be on him."
Lopez didn't embarrass himself on Saturday night, but he didn't play perfect defense, either.
He was charged with an error in the second inning when he mishandled a low, but catchable throw from third baseman Adrian Beltre, allowing Mike Napoli to reach base. Left-handed starter Ryan Feierabend pitched around the miscue, retiring the next batter to end the inning.
Otherwise, Lopez handled his first start at first base well.
He made the tag on a pickoff play that nailed Mark Teixeira in the first inning, made four other putouts on either throws or ground balls, and also had two assists.
"He did fine," Riggleman said. "Feierabend has a good move. He can pick the runner off, but he also can pitch the first baseman off. Jose stayed with it and made a nice throw to second [on a second pickoff in the second inning].
"I thought he handled himself real good."
Lopez said he borrowed a first baseman's glove from pitcher Miguel Batista, and the most difficult play he had in the game was when he had to station himself to be a cutoff man near the mound, but forgot where he was supposed to go on a ball that was hit into center field and drove in a run.
The Mariners have 15 games remaining, and exactly how many of those games Lopez would play at first base is uncertain. But Riggleman said Saturday night was not a one-time experiment.
"I am going to do it against some right-handed [starting] pitching," the manager said. "Whether we do it [ Sunday against Angels right-hander Ervin Santana], I don't know. But I don't plan on it being a one-day thing. I don't know how much we'll do it the rest of the year, but it's an opportunity to get Valbuena some playing time."
Lopez is still regarded as the team's primary second baseman now and in the future, but other personnel decisions must be made prior to the start of Spring Training next year.
Valbuena, a left-handed batter signed as a non-drafted free agent in 2002, started this season at Double-A West Tennessee and was promoted to Triple-A Tacoma. He batted a combined .302, scored 85 runs, hit 21 doubles, three triples, 11 home runs and 60 RBIs, earning a Sept. 1 promotion to Seattle.
"We're basically trying to create a way to get Valbuena in there and not have to use Jose as the designated hitter," the manager added. "We just want to see him play as much as we can without abandoning Lopez's at-bats."
Valbuena went 0-for-3 with a walk in Saturday night's game, and he's now 1-for-14 since joining the team.
Stay tuned for the next time Lopez gets a start at first base.
"If he's totally out of element there, and he says he doesn't like it, we might re-think it," Riggleman said before the game. "But we think he will be fine there, or we wouldn't do it. We still think of him as the second baseman next year."