Former closer Sean Marshall made his appearance in the eighth inning in relief of Johnny Cueto. The lefty faced only one batter, lefty hitter Robinson Cano, and struck him out on three pitches before exiting.
Logan Ondrusek faced two batters to finish the eighth after Marshall. Then it was Chapman time.
"I talked with him about a week ago and asked if he was mentally or emotionally ready in case this decision comes down," Baker said. "He told me he was."
Chapman faced four batters and used 15 pitches -- all fastballs in the 96-99-mph range. One batter reached on an error and the final batter -- Andruw Jones -- struck out on a 98-mph heater.
It was Chapman's second career save, with the other coming in a 13-inning game at St. Louis on July 6, 2011. He had eight saves for Triple-A Louisville in 2010.
"Either inning for me is the same," Chapman said of the eighth and ninth via interpreter. "I never feel extra pressure. Maybe one day when things get complicated, I could get some pressure."
Before the game, Marshall wasn't given any word on his status, but he was keenly aware that Baker was considering a change to Chapman. Marshall appeared willing to accept a different role.
"I'm a do-what's-best-for-the-team kind of guy," Marshall said. "I know what I do best and I don't plan on changing how I pitch in any different role. I'll keep doing that, whether it's as the closer, a setup guy or a one-out guy. Whatever it takes to win the game."
Just because Chapman is the closer, it doesn't mean he will always be the only guy for the ninth. For example, his availability for Monday vs. the Braves is already a mystery.
"I don't know. We'll see," Baker said. "I don't want to be answering that question today.
"We still have to monitor him about going back-to-back. It depends what kind of lineup they have, right or left."
Before the game, when asked if he might make future ninth-inning decisions based on matchups, Baker was opposed.
"I could but I'd rather not," Baker said. "Most good teams do [have one closer]. The bullpen by committee, I haven't seen it work too much. It makes my job harder. It makes their job harder. Everybody wants some continuity. Chapman is my No. 1 candidate, but he isn't as good the second day, and last year, he wasn't nearly as good the third day. The only problem is we may have to use him two days [in a row] and somebody else one day ... until we figure this out."
While giving up two runs and four hits, Marshall could not finish a save opportunity in the ninth inning of Saturday's 6-5 win over the Yankees. Jose Arredondo notched the final two outs for the save. Ondrusek also had to complete a save in Marshall's place on May 9 at Milwaukee.
Marshall is 1-2 with a 4.91 ERA with seven saves in 17 games and has allowed 22 hits over 14 2/3 innings. Chapman is 3-0 with a 0.00 ERA, seven walks and 39 strikeouts and has one unearned run and seven hits allowed over 22 1/3 innings.
"We've got some guys pitching well in the bullpen," Marshall said. "It's good they've picked up the slack. They've done that for me through the course of the first month and a half of the season. We'll just see how it goes. There are plenty of guys pitching well. I've enjoyed being the closer so far, but it's about what's best for the team. We want to win all season. We all want to do our part."