Nationals right-hander Dan Haren will start Tuesday’s game against the Dodgers, who will be throwing ace Clayton Kershaw.

No Nationals pitcher had a rockier start to the 2013 season than Dan Haren.

In Haren’s first three games, the right-hander surrendered 12 earned runs, including six in a 15-0 drubbing against Cincinnati. At the end of April, Haren had a 6.29 ERA — the worst among Washington’s starters.

But since his early struggles, Haren has improved his approach on the mound. He now is 4-3 with a 5.17 ERA and has won his past three starts.

It hasn’t been pretty at times, but Haren is starting to resemble the veteran pitcher Washington thought it was getting when the organization signed him to a one-year, $13 million contract in December.

When Haren’s hitting the strike zone, “he’s going to be tough no matter if it’s a good hitting club or not,” manager Davey Johnson said. “He’ll shut them down. He feels good about where he’s at and so do the rest of the guys.”

Haren’s best outing came in a 3-1 win over Atlanta on May 2. Haren went eight innings and allowed only one run on four hits. He threw just 90 pitches, with 62 for strikes.

In his most recent start, Haren faced a tough Detroit lineup. He held the Tigers to one run through five innings, even though he was shaky at times. But a poor pitch to Matt Tuiasosopo was crushed for a three-run home run, which cut Washington’s lead to 5-4. Haren and the Nats were able to hold on for the win, though.

“I really didn’t have much out there,” Haren said. “I was searching for it all game.”

Perhaps Haren’s early rough patch stood out even more in comparison to the red-hot starts of fellow starters Jordan Zimmermann and Ross Detwiler.

“When it happens at the beginning [of a season] it’s a little more glaring than in July or August,” third baseman Ryan Zimmerman said.

If there is any lingering concern about Haren, it’s that he has allowed a home run in each of his past three starts. But the righty was still able to earn wins over the Reds, the Braves and the Tigers — teams that entered Monday with a combined 63-47 record.

Having slowed some of the top offenses in baseball has helped Haren’s confidence.

“We’ve gone through a really tough part of our schedule,” Haren said, “and I like where we’re heading right now.”