Taijuan Walker is going on the 15-day Injured List with "right index finger inflammation" retroactive to Saturday, the Phillies announced on Sunday morning.
Right-hander Michael Mercado was recalled from Triple-A Lehigh Valley in his place.
Walker was tagged for three home runs in his last start on Friday night against Arizona, a 5-4 loss, and struggled to maintain his velocity.
Afterward, manager Rob Thomson mentioned a blister on Walker's right index finger, which lent to doubt over whether he would make his next start.
He won't now, which created an opening on the back end of the rotation that will go straight back to Spencer Turnbull, per The Athletic's Matt Gelb.
Turnbull is slated to start Wednesday in Detroit.
The Phillies' starting rotation overall has been one of baseball's best through 2024 so far, but Walker has stood as its most inconsistent link, posting a 3-3 record with a 5.60 ERA and a 1.49 WHIP in starts that have varied wildly.
Turnbull, meanwhile, will return to the fold with a 3-0 record and a 2.63 ERA that includes a scoreless three innings from Friday night.
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