That's what happened, as Scherzer came out of the bullpen in relief of Doug Fister to start the seventh inning, with the game tied at 3. Coco Crisp untied it with a one-out RBI single before Scherzer got out of the inning.
After the Tigers scored twice in their half of the seventh to take a 5-4 lead, Scherzer started the eighth by walking Brandon Moss, then allowed a double to Yoenis Cespedes and intentionally walked Seth Smith before striking out Josh Reddick and Stephen Vogt, then getting pinch-hitter Alberto Callaspo to line out to center fielder Austin Jackson on a 3-2 pitch to preserve Detroit's advantage.
"You know, I had to challenge [Callaspo] with my best pitch and I know he's a great fastball hitter, but I had to come with my best and he put a good swing on it and hit it hard," said Scherzer. "I thought it was down, but Austin made a great play to be able to run that play down, that was an unbelievable play."
The Tigers held on for the 8-6 victory, forcing a Game 5 and giving Scherzer his second win of the series.
"It was surreal to be able to get an out in that situation and keep the one‑run lead with bases loaded, no outs in the eighth inning," said Scherzer. "That's the stuff you dream of. Maybe it's not the ninth inning, but that's the stuff you dream about pitching: bases loaded, eighth inning, no outs, and I was able to do it."
Before the game, Leyland characterized Scherzer as a potential setup reliever who could carry a lead from starter Fister to closer Joaquin Benoit.
Scherzer's Game 4 appearance means Justin Verlander moves up to start in Oakland on Thursday night (8 p.m. ET on TBS). A scheduled off-day on Wednesday allows Verlander to pitch on his normal four days' rest.
That said, Leyland wasn't going to start Scherzer on short rest under any circumstances. He hasn't called on a starter to do that since he took over the Tigers in 2006, though he has had several instances where the question came up. It became a debate with Verlander during the AL Championship Series two years ago. It came up down the stretch in 2009, when Alfredo Figaro made a spot start against the White Sox on the next-to-last day of the regular season as the Tigers were struggling to hold onto a dwindling division lead.
Go back to 2006, and Leyland started then-rookie Verlander in Game 5 of the World Series rather than moving up Kenny Rogers, who could've started on regular rest thanks to a rainout. Leyland has repeatedly cited pitchers' health as a reason.
Asked if there was any thought of starting Scherzer in Game 4, like the Dodgers did with Clayton Kershaw Monday night, Leyland simply said, "No."
Scherzer has never started on short rest, but he did have a history in relief. He pitched 1 1/3 innings out of the bullpen in Game 5 of the 2011 ALDS at Yankee Stadium, in relief of Fister. He also had nine relief appearances as a rookie in Arizona in 2008.