SEATTLE -- Daisuke Matsuzaka left last night's start after four innings, the result of what the Red Sox termed "fatigue" in his right shoulder.

After giving up two runs in the first to the Seattle Mariners and another run in the third, Matsuzaka came out to begin his warmup tosses for the bottom of the fifth. After his second toss, he appeared to grab his lower back, bringing out a coterie of support from the visitor's dugout.

Following a brief discussion, Matsuzaka left the mound and the game.

"He felt some fatigue," said Terry Francona. "We're not going to run somebody out there (like that). There's just no sense in doing that."

The Sox manager was unsure whether Matsuzaka would be able to make his next start, which is slated for Monday in Baltimore. He will undergo further tests and examinations today.

Francona said he knew that Matsuzaka was experiencing an issue with the shoulder earlier and that the team was monitoring him. When there wasn't much life on his warmup tries, the Sox didn't hesitate to yank him from the start.

"Even before I went up on the mound," said Matsuzaka, "I felt things were a little off in the bullpen. I wouldn't go so far as to call it discomfort, but I wasn't at my best. I definitely felt there something wrong.

"I gave it a try, but I thought it best to stop . . . With so much season left and such a long way to go, we thought it would be best to come out of the game . . . Things just didn't' feel right."

Asked about his chances to make his next start, Matsuzaka said: "It's hard to say until we re-assess the situation until (today)."

Matsuzaka recalled that he had a "similar experience in the second or third year of my pro career," and that he had erred in attempting to pitch through that difficulty.

In 2002, which was Matsuzaka's fourth year in pro ball, he missed about half the season because of an elbow injury. It was not clear last night if that was the injury to which Matsuzaka had alluded.

Lugo, Francona tossed

In a bizarre development in the bottom of the fifth, shortstop Julio Lugo and Francona were both ejected by third-base umpire Angel Hernandez.

Lugo apparently took exception with Herandez’s ruling that Seattle DH Raul Ibanez checked his swing on a pitch by Aardsma. From his position at short, Lugo said something to Hernandez, who responded by tossing him from the game.

An enraged Lugo then rushed toward Hernandez to protest his ejection. Hernandez mostly ignored him as Francona raced out to defend his player.

Soon, Francona was gesturing and jawing in an animated fashion with Hernandez, and he, too, was ejected.

Alex Cora took over at short for Lugo, while Brad Mills managed the rest of the game for the Sox.

The ejections were the fifth and sixth for Red Sox personnel this year and third on the current road trip. David Ortiz, Manny Ramirez and hitting coach Dave Magadan had been run, with Magadan’s ejection taking place last Friday in Oakland.

Youkilis remains on shelf

Youkilis remained out of last night’s lineup against the Mariners for the second straight night, still hampered by some soreness in the top of his right hand. Once again, Sean Casey got the starting assignment at first.

Youkilis underwent precautionary x-rays late Monday, which proved negative, and still isn’t sure about the origin of the injury.

The Sox are hopeful that Youkilis can recover and be in the lineup today against Seattle lefty Erik Bedard. Then again, as Francona pointed out, lefties have actually hit Bedard better this year, batting .347 with just four stirkeouts in 49 at-bats, compared to right-handers, who are hitting .183 in 126 at-bats.

Cash cashes in at plate

Catcher Kevin Cash will get the start tonight with Tim Wakefield scheduled to start for the Sox.

Cash, who made the club over veteran catcher Doug Mirabelli in spring training, has been a surprise offensively, hitting .314, though, admittedly, he hasn’t had a great deal of playing time (51 at-bats).

Still, over his last five games, Cash is 6-for-19 and has reached base in 10 of his last 12 games with at least one at-bat.

That’s impressive for someone who came into this season with a career batting average of .167.

“He worked a lot over with winter with (hitting instructor Magadan),” said Francona. “I think having some success early (in the season) certainly helps, especially for bench players. But in spring training, his approach was good and it’s carried over.

“He doesn’t swing at a lot of balls and he’s gotten some big hits. We’ll see where he is at the end of the season, but he’s done a good job. He’s worked hard and it’s paid off.”

Extra bases

Red Sox lefty Jon Lester was named co-winner of the American League Player of the Week honor, sharing with Detroit’s Magglio Ordonez. Lester, of course, threw a no-hitter nine days ago against the Kansas City Royals. He joins Ramirez and Youkilis as previous winners of the award this season. … Ramirez jokingly invited teammates and media alike to a party in his hotel room Monday night to celebrate the occasion of his 2,000th career game, going so far as to shout out the room number for all to hear. According to the Elias Sports Bureau, among players who’ve reached that milestone, Ramirez is 10th in homers (498) and sixth in RBI (1,635). … Wakefield and pitching coach John Farrell spent some time on the field at midafternoon yesterday talking with Seattle pitcher R.A. Dickey, who also throws a knuckle ball.