T.J. Rivera’s transition to third base is a work in progress the Mets are willing to withstand.

Since moving to the position on a regular basis three weeks ago, Rivera has struggled with his fielding and throws, but is earning praise for his approach to the experiment.

“He knows he doesn’t have to be Nolan Arenado at third base to be a big league player,” infield coach Dick Scott said, referring to the Rockies’ Gold Glove third baseman. “[Rivera] looks at video and he’s out here doing the work and it might take time, but it’s going to happen. I have a lot of confidence in him.”

Rivera has six errors in 28 games at third base, but the Mets want to find out if he’s a viable option at the position for this season and beyond.

The Mets continue to like Rivera’s bat: He entered Friday’s game against Oakland with a .289/.333/.437 slash line with five homers and 25 RBIs. He then delivered two singles and drove in two runs for the Mets in their 7-5 victory over the Athletics.

“Honestly, I think [third base] is going to happen for him,” Scott said. “It might take some time. The worst thing we all can do on anything is say, ‘Next spring training we’re really going to get after this.’ Then three wasted months go by. I give him all the credit: He wants to do all the work. Every day he is finding me and we come out. That is all we can do.”

Neil Walker is expected to begin a rehab assignment Saturday for Triple-A Las Vegas in his comeback from a partially torn left hamstring. The veteran second baseman played a simulated game Friday at Citi Field.

The Mets’ .523 winning percentage in interleague play, is the best among National League teams. After this three-game series against Oakland, the Mets have interleague series remaining this season against the Mariners, Rangers and Astros.

Amed Rosario missed his fourth straight start for Triple-A Las Vegas because of a bruised finger he sustained earlier in the week.

Lucas Duda has one less error after an MLB scoring change from last Sunday against Colorado: Trevor Story was awarded a hit on a play in the eighth inning in which Duda originally received an error.