The Nationals have a deal in place to finalize perhaps the top starting rotation in baseball, agreeing to a one-year, $13 million deal with free agent right-hander Dan Haren, according to a person with knowledge of the deal. The agreement was first reported by

Haren still needs to pass a physical for the deal to become official. The physical, Haren said in an e-mail, will take place Thursday. But Haren said he has already taken a physical for another interested team, and he checked out fine.

“The team was much less concerned about me physically after looking at me,” Haren said in an e-mail to the Post.

Haren expressed complete confidence in his health and clarified the issues he faced Haren tweaked his back in spring training last year, which, after he pitched through it for the first half of the season, led to him landing on the disabled list for the first time in his career. Other teams who pursued him worried about the condition of his hip, but Haren said  he has pitched with the issue since he was a young pitcher in Oakland.

“As for my health I feel great,” Haren said. “I actually felt great towards the end of last year, and I was battling my mechanics a lot but was still getting good results. I guess teams were concerned of a hip issue that I’ve dealt with since my time in Oakland. It never has and never will cause me to miss time.”

Haren, a three-time all-star, would give the Nationals a veteran workhorse to place into a rotation that includes four 20-something flamethrowers in Stephen Strasburg, Gio Gonzalez, Jordan Zimmermann and Ross Detwiler.

“This will probably be the best rotation I’ve ever been a part of,” Haren said. “I’m confident I’ll hold up my end and I think that the sky is the limit for this team. It’s gonna be fun to get going and I can’t wait to get to Florida.”

The rotation helped lead Haren to the Nationals. Haren chose the Nationals because he believes that, after a 98-win season in 2012, they are the favorite to win the World Series next year.

“The deciding factor in coming to Washington was winning,” Haren said. “I don’t think there’s a team better positioned to win now. It really was an easy decision for me actually, It didn’t take me long to decide that playing for the nationals made sense.”

The Nationals’ offseason to-do list now contains only two unresolved matters. They need to add to their bullpen, and they need to either re-sign Adam LaRoche or decide to give their first base spot to Michael Morse.

Haren, 32, went 12-13 with a 4.33 ERA for the Los Angeles Angels last year as he pitched through back problems. The injury concerns convinced the Angels to not exercise a one-year, $15.5 million team option for 2012, instead giving him a $3.5 million buyout.

But Haren had long been one of the best, most durable starters in baseball. As he bounced from the Athletics to the Diamondbacks to the Angels, Haren averaged 226 innings with a 3.49 ERA. Unlike the rest of the Nationals’ rotation, Haren relies more on cutters, changeups and control. In his career, Haren has walked only 1.9 batters per nine innings, while striking out 7.6.

“Great athlete, outstanding stuff, gamer,” Manager Davey Johnson said. “He fits right in. I know he can swing the bat.  So if we get that finalized, he’ll be a great addition.

“I’ve got some young guys that act like veterans, and they pitched like veterans last year for me, and a veteran like Dan Haren is just going to make things even better. I think he’s a great addition. I’ve seen him pitch a lot over the years, intense competitor, and hopefully we’ll get that done.”

Haren lost velocity on his fastball this season, averaging 88.5 miles per hour compared a career average of just over 90. Some scouts believe began before his injuries struck, which would add to the injury risk. But Haren also provides an enormous upside for a relatively small guaranteed sum.

The Nationals had interest in going after both Zack Greinke and James Shields, but they found the cost – money in Greinke’s case and players in Shields’ – to be extraordinary. With long-term commitments to Bryce Harper, Strasburg and other young stars needed in coming years, the Nationals saved money and kept their young core intact.

And they still signed a pitcher who, when healthy, is comparable to fellow right-handers Greinke and Shields. From 2008 through 2011, Haren ranked seventh in the majors in wins above replacement, per, with 23.0 – essentially even with Greinke’s 23.4 and well ahead of Shield’s 14.6. The Nationals were able to land Haren with a one-year deal that, even if Haren flops, will do them no long-term harm.

The agreement works well financially for Haren, too. The Angels could have kept him by exercising a $15.5 million team option for 2013, but they instead chose to buy him out for $3.5 million. Between the buyout and the deal with the Nationals, Haren will make $16.5 million — $1 million more than he would have if the Angels picked up his option.