Chirinos, who will start Sunday's game against the Twins, has also been officially named the Rays' No. 4 starter, Bill Chastain of MLB.com reports.
Chirinos had previously been confirmed as Sunday's starter without actually having been designated as an official member of the rotation. That changed late Saturday afternoon, when manager Kevin Cash told reporters that Chirinos had built up his endurance to the point where he could take the mound every fifth day. "I just think where he got built up with his pitch count, he's comfortable now that he can provide right around that 100-pitch count," Cash said. "We've been going back and forth with it. It's not the easiest thing in the world to build these guys up...I think we're in a better spot now with Yonny in the rotation."