The Red Sox’ Kevin Youkilis, hustling for a double during a recent game against the Royals, has been undergoing treatment on the top of his right hand.

The Providence Journal / Bob Breidenbach

SEATTLE — Kevin Youkilis missed his third straight game last night, but is expected to return to the lineup tomorrow night when the Red Sox begin a four-game series against the Baltimore Orioles at Camden Yards.

Youkilis has been troubled by inflammation of the right hand since earlier in the week. He was removed from the lineup Monday afternoon, replaced by Sean Casey. Casey had a three-hit game Tuesday night in the 4-3 loss to Seattle and had a hit in Monday’s game, too, making him 4-for-8 in the two games.

Casey faced lefty starter Erik Bedard last night.

“It’s slowly progressing,” said Youkilis yesterday. “I can still feel it a little when I make contact. They didn’t want me to play (last night, with the off-day looming today) and aggravate it.”

“I thought about playing him,” said manager Terry Francona. “But I don’t think it makes a lot of sense with the day off. Let’s let him get another day. But he feels better.”

He’s been undergoing treatment here, getting heat, ice and stimulation on the top of the hand.

“I’ll be OK,” he said. “I’ll be back in there (tomorrow).”

Manny stays loose

After Manny Ramirez hit career homer No. 499 Tuesday night — a three-run belt in the sixth inning — there was anticipation that he could become just the 24th player in baseball history to reach 500 career homers last night.

According to research, only seven players in baseball history have hit their 499th and 500th homers in consecutive games — Barry Bonds, Babe Ruth, Willie Mays, Frank Robinson, Mark McGwire, Mike Schmidt and Ted Williams.

“He’s a great hitter who has hit for a lot of power,” said Francona before the game, “and his next homer kind of validates that.”

Ramirez was his usual loose self before the game, joking with teammates and lovingly admiring a new shipment of bats.

“Hey, Case,” he called out to Casey, “I’m not going to hit my 500th tonight because the press conference will take too long and we have to get to Baltimore. I’ll do it in Baltimore.”

Ironman Pedroia

Dustin Pedroia has appeared in every one of the team’s first 56 games — 54 in the starting lineup and two off the bench.

Since 1956, only three other Red Sox second basemen had appeared in every one of the game’s first 56 games — Chuck Schilling (1961, 1963), Marty Barrett (1986, 1988) and Jody Reed (1992).

Over the last half-century, Barrett holds the club records for consecutive games played at the position — 99 — from April 7-July 29, 1986.

Around the bases

Though the Sox still lead the American League in road batting average (.271), they went into last night hitting just .186 on the current trip, while averaging just 2.8 runs per game. … J.D. Drew got the night off against Bedard. Jacoby Ellsbury was in right field, with Coco Crisp in center. Ellsbury hit leadoff, with Crisp batting seventh. … Reliever David Aardsma, who pitched 1 1/3 innings Tuesday night, walked two and has now issued 18 walks in 24 1/3 innings this season.

smcadam@projo.com