MINNEAPOLIS -- If the Chicago Cubs are going to start young pitchers, then they have to live with the growing pains that Carlos Marmol went through Friday night.

Marmol gave up seven runs on six hits and four walks -- with three of the four walks scoring -- as the Minnesota Twins beat the Cubs, 7-2, in front of 34,361 at the Metrodome.

"Tonight was a rough night," Chicago's Phil Nevin said. "We went up against a team that's playing great baseball and had their ace on the mound. We gave them some runs early -- not a good combination."

Justin Morneau drove in three runs to back Johan Santana as the Cubs dropped to 8-16 against southpaw starters. Santana (8-4) gave up five hits, including a leadoff homer to Nevin in the second, over eight innings. The lefty walked one and struck out six.

His last strikeout was in the eighth when he got Aramis Ramirez swinging to strand two runners.

"You see the numbers he puts up, and everybody knows what he can do," Nevin said of Santana. "When he has to make pitches, he doesn't get in trouble very often. When he does, the good ones seem to rise to those occasions. He had one tough jam, and to reach back when he has 100-something pitches and make the pitches to [Ramirez] is pretty impressive."

Marmol (1-2) has the potential to do that as well. The rookie took the loss in his third start, giving up seven runs on six hits and four walks over 5 2/3 innings. The Cubs now are 3-8 in Interleague Play.

"Walks always hurt," Cubs manager Dusty Baker said. "He was throwing the ball, and sometimes he was throwing real well and sometimes he couldn't find the plate. All those rallies were preceded somewhere by a walk. That's what you have with young pitchers, most of them have trouble commanding the strike zone. He has the stuff. He just needs experience and throw more strikes."

Marmol acknowledged the walks were a problem.

"I gave it the best I can," the rookie right-hander said. "That's what I do, to go out and pitch."

He's not thinking about being demoted to the Minor Leagues or going to the bullpen.

"We've been going through growing pains with all of them," Baker said of the Cubs' rookie pitchers. "Preferably, you'd like him out of the bullpen and in long relief. We are what we are, we have what we have."

After Nevin's homer gave the Cubs the lead, Marmol walked Michael Cuddyer to open the Minnesota second and Morneau followed with his 19th home run to put the Twins ahead, 2-1.

With one out in the Twins' third, Nick Punto singled and Joe Mauer walked, and both scored on Cuddyer's double down the left-field line. Cuddyer got to third on the throw home, and scored on Morneau's single to take a 5-1 lead. Luis Castillo added a two-run single in the Twins' sixth.

The Cubs had runners at first and second with one out in the eighth when Neifi Perez bounced a ball over Santana. Shortstop Jason Bartlett fielded the ball but overthrew first for an error, allowing a run to score.

It will be interesting to see what the Cubs do with Nevin when Derrek Lee returns. Lee is scheduled to begin a two-game Minor League rehab assignment Saturday at Triple-A Iowa.

"This team will be a lot better when Derrek does come back," Nevin said. "I'm part of this team and whatever I'm asked to do when Derrek does come back, I'll do it. Obviously, he'll be the first baseman. I know that. It makes this team better when he's healthy and in there."