Chavez, who struck out all three batters he faced in Tuesday's loss to the Diamondbacks, has pitched four perfect innings with six strikeouts since joining the Cubs on Saturday.
The Cubs needed a bullpen boost with several relievers dealing with injuries, and Chavez has delivered in his first three appearances since the team acquired him in a trade Thursday. The 34-year-old righty has a solid 3.28 ERA this season and figures to remain a key member of the Chicago relief corps the rest of the way.