"I took a foul ball off there and it got me in the right spot," said Zunino, wearing a brace on the wrist postgame. "I will get re-evaluated in the morning. I'm feeling better already. We'll just take it day by day."
Acting manager Robby Thompson said Zunino was already hurting in that same area from a foul ball two days earlier and the decision was made to take him out with the team already sporting a 6-0 lead.
"I've taken balls off me everywhere in the last couple days," Zunino said. "But this one sort of got me in the same spot and sort of re-aggravated it a little bit. But it's not too bad."
Zunino, last year's third overall Draft pick, has been Seattle's primary starter since being called up from Triple-A Tacoma six weeks ago.
The 22-year-old was 1-for-2 with an RBI single on Thursday and is hitting .242 with two home runs and 10 RBIs in 99 at-bats over 29 games.
Blanco, 41, is the only other catcher on the 25-man roster. He went 1-for-2 with a double after replacing Zunino and is batting .171 in 70 at-bats this season.
Jesus Sucre is on the 15-day disabled list, still recovering from a bruised wrist that occurred in early June. Jesus Montero, who opened the year as Seattle's starting catcher, has just rejoined Tacoma after missing more than a month following surgery on a torn meniscus in his right knee. But Montero will be limited to first base and designated hitter duties the remainder of this season.
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.