KANSAS CITY -- Rather than sitting around his hotel room, manager Bobby Valentine took a field trip on Tuesday morning as he received a guided tour of the Negro Leagues Baseball Museum in Kansas City.

It was an experience Valentine won't soon forget.

"Great, it was great. I think everyone should go, yeah. It was my first time," Valentine said. "It's spectacular."

What in particular stood out for Valentine?

"I like how they defined the most important moments of the league's history and how it paralleled with the growth and development of our country," Valentine said. "The demise of their league and growth of our country -- they run kind of parallel paths."

With the All-Star festivities set for Kansas City in July, Valentine suggests that the museum expand its hours so it can accommodate everyone who wants to see it.

"I hope they go 24/7," Valentine said. "I would recommend that those four days they recommend every hour of the day and get the busses there at 4 in the morning."

Middlebrooks: Hamstring tightness not serious

KANSAS CITY -- Will Middlebrooks looked poised to carry his hot hitting into his fifth Major League game when he belted a double to right in his first at-bat on Tuesday night against the Royals.

But after scoring on a single by Kelly Shoppach later in that second inning, Middlebrooks was removed from the Red Sox's 6-4 loss to the Royals with tightness in his left hamstring.

It is the second time in four days Middlebrooks has dealt with discomfort in his leg, but the Red Sox are confident it is nothing serious.

In fact, Middlebrooks could be right back in the lineup for Wednesday night's finale of this three-game series.

"It's nothing serious. It's not a big deal. It was just a precautionary thing coming out of the game, so hopefully I'll be back in there tomorrow," Middlebrooks said. "It was just a type of cramping, tightness in the hamstring, so we really didn't want to mess with it. Just wanted to be safe."

When the Red Sox took the field for the bottom of the second, Nick Punto was inserted at third base.

Middlebrooks, who missed Saturday's game with leg cramps, has been a hot topic around the Red Sox, and with good reason. He is hitting .409 with three homers and nine RBIs.

The man Middlebrooks is replacing in the lineup with the Red Sox -- third baseman Kevin Youkilis -- is making some progress with his back injury.

While manager Bobby Valentine hadn't yet had a specific report on Youkilis by the time he met with the media on Tuesday, his impression was that the third baseman was making nice improvements and could be ready to join Boston's roster soon.

"I think that's the case," said Valentine. "Absolutely."

Youkilis is eligible to return to the roster on Monday. He recently started on a walking program that focused on strengthening certain areas of his back.

"It's a stimulated walking exercise program," Valentine said. "It's forward and back and balancing and with all the movements that you need rather than just left in front of right -- and I think there's been more of that today."

If Youkilis returns soon and Middlebrooks is still swinging a hot bat, the Red Sox could be faced with a tough decision.

Is there a scenario in which Middlebrooks and Youkilis could both be on the roster and get significant playing time?

Perhaps one way would be for Middlebrooks to learn how to play in the outfield. Though Valentine said the discussion hasn't been formally been brought to the table, he theorized that it wasn't the most outlandish scenario.

"It's been tossed around in some quarters," Valentine said.

From Valentine's experience, corner infielders trying to play the outfield hasn't always been pretty. In fact, Youkilis demonstrated that when he was asked to do it in the past on an emergency basis. But perhaps Middlebrooks could be one of those exceptions.

"He's more fleet," Valentine said. "He runs a little better than a lot of third baseman, which might give him a little upside. It's just a little different. It hasn't been a tabled discussion yet, so I don't think it even has to enter his domain. That being said, I think he's a pretty -- again small sample -- but my being around him is he's a pretty mature baseball guy. He's not going to be flustered by a lot of things."

Facing another lefty, Salty, Sweeney sit again

KANSAS CITY -- It isn't very often a team faces only left-handed starters in a three-game series, but that is what the Red Sox have on the table during this visit to Kansas City.

So for the second straight night, Kelly Shoppach caught for the Red Sox, while Darnell McDonald played the outfield instead of the left-handed-hitting Ryan Sweeney.

"[Shoppach] swung the bat well last night, and you know, this is a hard-throwing lefty. It should be nice to see," said manager Bobby Valentine.

However, expect Jarrod Saltalamacchia to start behind the plate Wednesday night against lefty Bruce Chen. Josh Beckett pitches the opener of the homestand at Fenway on Thursday, and Valentine likes to pair him with Shoppach, even though Boston will be facing righty Derek Lowe that night.

Sitting Sweeney, who is hitting .368, for two straight days can't be easy. In a small sample size, Sweeney is 1-for-10 against lefties this season. Still, it's hard to imagine he won't start Wednesday.

"It's not really avoiding [Sweeney]," said Valentine. "I'm trying to keep him as fresh as possible, especially with his lower body. We have a string here, so he's going to be asked to play a lot of games in a row. It's kind of interesting, isn't it? Yeah. It's not an easy determination. Actually, Ryan felt good against this kid tonight. [Danny] Duffy is a hard thrower, but I think Ryan can hit anyone.

Red Sox enthused by Ellsbury's progress

KANSAS CITY -- There seems to be a bounce in Jacoby Ellsbury's step these days, as he spends his time doing one rehab drill after another.

Before Tuesday's game against the Royals, Ellsbury was doing a series of agility drills on the field.

"This is the beginning of the next step in his program, where he's able to swing his arm and make all of those movements, agility-wise," said manager Bobby Valentine. "They're really excited about his acceleration."

Ellsbury suffered a subluxation of his right shoulder on April 13. The earliest he could return in the estimated timetable was about six weeks, which would be around May 25, when the Red Sox open a homestand against the Rays.

It's still too early to tell if he will be back by then.

Valentine isn't sure when Ellsbury will start doing more baseball-specific activities, but it could be soon.