PHOENIX — Trevor Williams will jump into the Mets’ rotation for a cameo on Saturday.

Following his team’s 6-5 victory over the Diamondbacks in 10 innings Friday, manager Buck Showalter named the right-hander Williams as his Saturday starter. The Mets need the extra starter following the rainout that forced a Tuesday doubleheader against the Giants at Citi Field.

Tylor Megill will remain on regular rest and pitch Sunday’s series finale. Max Scherzer, who pitched the nightcap Tuesday behind Megill, will receive an extra day of rest and open Monday’s series in St. Louis.

Williams has pitched twice in relief for the Mets, last appearing on Sunday, and could stretch out for multiple innings.

“He would be more than an opener,” Showalter said.

Taijuan Walker threw a side session and could be in position to rejoin the rotation within the week. The right-hander, who is returning from shoulder bursitis, pitched in a rehab game on Wednesday. Showalter said team officials will reconvene Saturday to decide on a plan.

The Mets have won each of their first four series to start the season for only the third time in franchise history. The club record is five series, set in 2018, according to the Elias Sports Bureau. The Mets also won four straight series to begin the season in 2006.

Showalter, who managed the Diamondbacks from 1998-2000 — he was hired at the franchise’s inception — said he’s still struck by the number of familiar faces at Chase Field.

“There’s a lot of people still here that we brought in, I feel good about that,” Showalter said. “From the groundskeeper to the clubhouse guys, I see a lot of them, it’s been fun.”