With the Boston Red Sox leading the New York Yankees 4-1 entering the bottom of the eighth, there was an odd sight in Boston's bullpen in Game 4 of the American League Division Series: staff ace Chris Sale warming up.

Sale then entered when the Red Sox took the field. He threw a perfect inning, retiring Gleyber Torres, Andrew McCutchen, and Aaron Hicks on 13 pitches. Sale even struck out Hicks on his trademark slider. Craig Kimbrel allowed two runs before closing out the ninth to earn the save to eliminate the Yankees. 

Sale had started Game 1 and would have been in line to start a decisive Game 5. Yet manager Alex Cora didn't want to risk the series reaching that point. Hence playing the Sale card early. 

Sale, of course, began his big-league career as a reliever. His first 79 appearances in the majors came out of the bullpen. Yet more than seven years have passed since he was last a full-fledged reliever, with his most recent regular-season relief outing coming in May 2012. That appearance was precipitated by a sore elbow that clearly turned out to be no big deal. 

Sale did pitch out of the bullpen last postseason, permitting two runs in 4 2/3 innings against the Houston Astros. He was charged with the loss in Game 4 of that series. Do note that Cora was on Houston's bench last October when Sale worked in relief. Also note that Astros manager A.J. Hinch used his starters -- including Justin Verlander and Charlie Morton -- in relief to great success throughout the postseason. It worked then for the Astros, and it worked on Tuesday for the Red Sox.

As a result, the two teams will meet in the upcoming American League Championship Series.