SANTA CLARA — Colin Kaepernick and the San Francisco 49ers are looking forward to matching up with Tom Brady and the prolific offense of the New England Patriots on Sunday night.

It may be more a matter of keeping up.

After breakout performances in Kaepernick’s first two NFL starts, the San Francisco offense lacked rhythm and punch the past two weeks as the 49ers lost in overtime to the St. Louis Rams and struggled for three quarters before finishing off the Miami Dolphins.

The Niners realize they likely will need more this week with the NFL’s top-ranked offense on the other sideline. And it’s another prime time opportunity for San Francisco’s 12th-ranked attack to show what it can do now that Kaepernick has settled in as the team’s starting QB.

“This is a showdown we’ve been waiting for, and we’ve got to put points on the board,” tight end Delanie Walker said Wednesday. “We know New England’s got an explosive offense, and we can be the same with Kap. One thing we’ve got to do as a team is keep our offense on the field and keep our defense on the bench. That’s the main focus this week.”

The last time the 49ers played in a nationally televised evening game, Kaepernick lit up the Chicago Bears in his starting debut Nov. 19 to spark San Francisco in a 32-7 rout. The next week, Kaepernick passed for a touchdown and ran for another as the Niners put up 31 points in a win at New Orleans.

Those are San Francisco’s highest scoring outputs since the first week of October, when Alex Smith was the team’s starting quarterback. But things haven’t gone as smoothly the past few weeks, when the 49ers had their least productive offensive performances since slipping past Seattle in another prime-time game Oct. 18.

The 49ers even experienced problems getting to the line of scrimmage on time last week, when they converted on just two of 10 third-down plays and didn’t secure a 27-13 victory over the Dolphins until a late offensive charge produced two fourth-quarter touchdowns.

Kaepernick led the charge and sealed the win with a 50-yard touchdown dash with 2:10 to play, his second consecutive game with a 50-yard run, the longest by a quarterback in franchise history. Against the Patriots, the 49ers may rely more on the big-play ability that gave Kaepernick the starting job over Smith, the NFL’s third-ranked quarterback who hasn’t played since suffering a concussion on Nov. 11.

“There are definitely things that we’re doing that tailor the offense to his skill set,” coach Jim Harbaugh said.

Kaepernick is 3-1 as a starter but this Sunday is the biggest stage yet for the second-year pro. As is his style, Kaepernick displayed little emotion and was brief with his answers when talking about the Patriots on Wednesday.

“It’ll be a great challenge for us,” Kaepernick said. “It’s a great opportunity to go out and show what we’re capable of. They’re going to give you a lot of different looks on defense. You just have to be ready for it, for their disguises and different coverages, different fronts they’re going to give you.”

Kaepernick was ready for much of what he saw during his first month as a starter. He’s completing 67.4 percent of his passes and is averaging 217 yards passing per game and 8.3 yards per pass attempt as a starter. He’s thrown just one interception in 129 attempts this year and has a passer rating of 97.4.

And despite not playing in three games and having 13 combined carries in five others, Kaepernick is third among NFL quarterbacks with 351 yards rushing and five touchdowns on the ground.

The 49ers figure to need everything they can get from Kaepernick and the NFL’s second-ranked rushing attack to match up with the Patriots.

“You have to rise to the occasion and play your ‘A’ game,” said left guard Mike Iupati. “They have a great offense so they’re going to score points. What we need is to match their points. Our offense has to go out there and execute our plays and do what we do best.”

San Francisco’s second-ranked defense leads the NFL in fewest points allowed, surrendering just 14.2 per game. But the Patriots lead the league with an average of 36.3 points a game, and they’ve scored 42 or more points in four of their past six games.

That has even San Francisco’s stoic defenders anticipating that they might need more help this week from the team’s offense.

“That’s what it’s going to take,” cornerback Carlos Rogers said. “It’s going to take our offense moving the ball on them, running the ball, keeping Brady off the field. However it turns out, as long as we keep Brady on that sideline and not on the field, it’s going to help us out a lot.”