TORONTO -- Michael Morse was batting fifth and was the Nationals' designated hitter for Monday's series opener against the Blue Jays.

Monday marked the fourth consecutive game that Morse was the team's DH after starting all three games at the position during Washington's three-game set at Fenway Park in Boston this past weekend.

Morse played in just his 10th game this season after missing the first two months of the year recovering from an injured right lat muscle.

Nationals manager Davey Johnson said Morse provides the team some much-needed power, something especially vital to the club with veteran Jayson Werth sidelined.

"[Morse] still has a lot of respect around the league," Johnson said. "His presence in the lineup is a good presence. Him hitting in the middle of the lineup is a good boost to us."

Morse entered Monday's contest batting .188 with no homers and two RBIs, but Johnson chalked up the slow start to the amount of time that his slugger missed, and he believes Morse will be just fine as he gets more games under his belt.

"He's a good hitter, but for big, strong hitters, it usually takes them a little longer to get going and feel comfortable," Johnson said. "He had a good [batting practice] session today early."

The 30-year-old Morse had a career year in 2011, batting .303 with 31 home runs, 95 RBIs and a .910 OPS.

Storen feels good after second mound session

TORONTO -- Drew Storen threw off a mound Monday for the second time since undergoing surgery to remove bone chips from his right elbow, and there were no reported setbacks.

Nationals manager Davey Johnson is pleased with the progress his closer is making and seems optimistic -- while not naming a date for his return -- that Storen will be ready to come off the disabled list after the All-Star break.

"He's fine, no problems afterward," Johnson said. "I think he was a little disappointed because he thought he threw a little bit better than he felt. ... But I wouldn't expect anything less. Every time he throws the ball, he wants to throw it through the wall. But he had no problems throwing, so he is right on track."

Storen, who has missed the entire season, had his first mound session on Friday.

The 24-year-old saved 43 games for the Nationals in his second big league season in 2011.

Mattheus to continue rehab work Tuesday

TORONTO -- Nationals reliever Ryan Mattheus is expected to pitch again on Tuesday as he continues on a rehab assignment at Class A Potomac.

The right-hander allowed two home runs in one inning of work Sunday in his first outing since landing on the 15-day disabled list with a plantar fascia strain in his left foot.

"He is doing fine," manager Davey Johnson said. "He will probably go an inning, or maybe a little bit more than an inning. We will see how he does and take it from there."

Johnson wouldn't speculate if Mattheus will return to the Nationals once activated, and stressed the club will take a wait-and-see approach with the 28-year-old.

"The main thing is not to rush him," Johnson said.