For the Mets, fixing Ruben Tejada’s defense isn’t just a priority, it’s a must.

With no other viable options at shortstop, they need the 23-year-old to break out of his fielding funk. If the past week is an indication, he’s finally taking small but vital steps toward doing just that.

Tejada has not made an error in his past three games, and he shook off Friday’s ankle injury that reduced him to a pinch-hitter Saturday to turn in an outstanding defensive effort Sunday. It was hardly Gold Glove stuff, but it was a vast improvement on his rash of six errors in the season’s opening 13 games.

“We know what kind of defense he can play,’’ said third baseman David Wright, whose Mets open a series against the Dodgers tonight. “Everybody goes through that ... especially early in the year where you’ve got the adrenaline flowing. You make a couple errors, and all of a sudden you start thinking about it and expand the problem.

“But we’ve seen the plays he can make. I’ve seen the defense he brings to the table. It’s not just offensively — he gets on base, does a nice job, had a big walk (Saturday) — but also defensively he’s great. So I wasn’t worried at all. Just a slow start.’’

Slow is being kind. When Tejada sailed a throw over Ike Davis’ head a week ago in Colorado for his sixth error, it plated the two tying runs with two outs in the eighth inning of a come-from-ahead 9-8 10-inning loss to the Rockies.

The six errors were the second-most in the majors going into last night, a shocking start for a player who finished with the third-best fielding percentage among NL shortstops last year. But with minor leaguer Omar Quintanilla the only other option, both Wright and Terry Collins have professed faith in Tejada.