SANTA CLARA, Calif. >> The frustration from back-to-back playoff losses to San Francisco that both ended on odd plays turned to humiliation for the Dallas Cowboys.

Hoping to prove themselves against a fellow NFC contender in a showdown against the 49ers, the Cowboys were run off the field almost from the start.

The defense that had been so stingy the first four weeks was completely exposed. The offense took more than a quarter to gain even a single first down and couldn’t move the ball or protect it.

It added up to a 42-10 loss to the 49ers on Sunday night that was the most lopsided ever for Dallas in this storied rivalry and that raised more questions about whether the Cowboys are a viable threat to get back to the Super Bowl for the first time in more than a quarter-century.

“It’s a punch in the gut, it’s a kick the in the (butt), whatever phrase you want to put on it,” coach Mike McCarthy said. “They beat us in all three phases.”

Dak Prescott was under pressure from San Francisco’s relentless defense right from the start as the Cowboys (3-2) began the game with three three-and-outs and a lost fumble by Tony Pollard.

Prescott responded with a 26-yard TD pass to KaVontae Turpin in the second quarter to provide a glimmer of hope but everything fell apart in the second half, leading to Dallas’ most lopsided loss in 10 years and biggest ever against San Francisco.

After San Francisco extended the lead to 28-10 on Brock Purdy’s third TD pass of the game midway through the third quarter, Prescott heaved a deep pass on first down into double coverage, leading to an interception to Tashaun Gipson.

That set up another Niners touchdown and Prescott then threw interceptions on the next two drives, giving him three in a span of just six offensive plays.

“Didn’t see it coming,” quarterback Dak Prescott said. “Put everything into this, and got punched in the mouth. It was humbling a couple weeks ago against Arizona. But this may be the most humbling game I’ve ever been a part of. Felt good about the preparation, felt good about everything honestly coming into this game and they beat us in every aspect.”

It’s now three straight wins in the series for San Francisco. The Niners won a wild-card game in Dallas in the 2021 season that ended when Prescott scrambled and then couldn’t spike the ball in time for a final play in a 23-17 loss.

The Cowboys lost again in the divisional round last season on the road 19-12 with the game ending on a play that featured running back Ezekiel Elliott at center that never had a chance.

This game had no drama at the end as most of the starters for both teams spent the bulk of the fourth quarter as spectators.

It was Dallas’ most lopsided defeat since losing 49-17 to New Orleans in 2013 but the Cowboys aren’t ready to concede anything to the Niners and are hopeful for another January rematch.

“We are not that far off from them,” star edge rusher Micah Parsons said. “I do not think they are this much better of a team than us. We beat ourselves, and we need to be in better position to make plays and things like that. But going forward, we’re going to have to adjust and get ready. Because I definitely feel like they had our number and we didn’t have theirs. They gave us their best shot tonight, and we get to learn from this and get better come playoff time.”