There's been a ton of talk and numerous names thrown around since the Dallas Cowboys lost backup QB Kellen Moore to a broken ankle.

Nick Foles. Michael Vick. Johnny Manziel!

The speculation on who'd back up Tony Romo ranged from the sublime to the absurd. On Saturday night, Dak Prescott seemingly put an end to all of that.

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The rookie from Mississippi State shone for the first half of Dallas' preseason opener at L.A., completing 10 of 12 passes for 139 yards and two TDs, with both incompletions coming on drops by Geoff Swain.

Prescott hooked up with Dez Bryant on a 10-yard score against cornerback Coty Sensabaugh in the first quarter ...

Defenses beware.@DezBryant is doing @DezBryant things.

And there's nothing you can do about it. #DALvsLA https://t.co/7FxizeqZxl

— NFL (@NFL) August 14, 2016

... then lofted a perfectly placed 32-yard throw over Lamarcus Joyner to Terrance Williams en route to a 21-7 lead.

.@15_DakP out here looking like a Pro Bowler...

Another perfect TD pass from the rookie! #DALvsLA https://t.co/WQKIAsaEK5

— NFL (@NFL) August 14, 2016

Dak Prescott is making the new LA Rams look like La Tech.

— Bruce Feldman (@BruceFeldmanCFB) August 14, 2016

Prescott sat out the second half as the Cowboys' other backup, Jameill Showers, led the offense. And Showers was capable, finishing 8 of 16 for 99 yards and showing good mobility. And turning in the most exciting play of the night:

When you think you have Cowboys QB Jameill Showers sacked, but it turns into a 47-yard completion...

HOW? #DALvsLA https://t.co/faIIBA206H

— NFL (@NFL) August 14, 2016

But the offense stalled and the Rams rallied for a 28-24 win behind Sean Mannion -- the seemingly forgotten man in the Rams' QB competition.

However, Prescott's performance had to give the Cowboys confidence that they had found their backup QB.

"The best thing about Dak is that he is extremely calm," Bryant said. "It's like he's been here before. He's not playing like a rookie. He is going to be very good. He's special."

The Associated Press contributed to this report.

.@JaredGoff16. @15_DakP.

Rookie respect. 💯#DALvsLA pic.twitter.com/Ob9buiOroR

— NFL (@NFL) August 14, 2016

Every throw from Dak Prescott's impeccable @DallasCowboys debut! 👇 #DALvsLA https://t.co/ux6hQG4SbL

— NFL (@NFL) August 14, 2016