He appreciated the vote of confidence by his club, especially after making his second All-Star game and first since 2001. Guzman, who will earn $8 million in each of the next two seasons, could have opted to test free agency this fall.
"I took this deal because I want to stay here," said Guzman, in his third year with Washington after spending his first six major league seasons with the Minnesota Twins. "They gave me the deal I wanted. Why do you have to wait? I take the deal."
The 30-year-old Guzman entered Tuesday night's series opener at San Francisco batting .310 with five home runs, 34 RBIs, 56 runs scored, three triples and 26 doubles in a team-high 96 games this season.
A switch-hitter, he also led the National League with 129 hits entering play Tuesday, and he had 25 hits with runners in scoring position to lead the team.
"I was looking for a longer deal but I understand that," Guzman said. "I had my problems a couple years ago."
He was referring to missing the 2006 season with a shoulder injury.
Also Tuesday, the Nationals reinstated third baseman Ryan Zimmerman from the disabled list and his rehab assignment with Triple-A Columbus. Washington also recalled right-hander Garrett Mock from Columbus and optioned second baseman Emilio Bonifacio to the Triple-A club. Bonifacio was acquired from Arizona earlier in the day for reliever Jon Rauch.
Zimmerman had been on the disabled list since May 26, with a small tear of the labrum in his left shoulder.
"It's been a long time," Zimmerman said. "We've been scoring and winning a lot. I hope I don't mess anything up. We've got to just continue to play how we're playing. I want to go right back to where I was. ... I'm not going to come back and play tentative."
Zimmerman was in the lineup and batting third. The Nationals had considered activating him sooner but opted instead to give him a little bit of extra time so "I wouldn't hurt them when I was thrown back in the lineup," Zimmerman said.
"He brings a lot to the table," general manager Jim Bowden said. "We're a better team with him."