The Boston Red Sox got a good laugh, watching the rookies put on the “High School Musical” tank tops and thrift-store threads for the plane trip south.

OK, playtime is over. There’s a division title to be won.

Starting Monday night, the defending World Series champions open a three-game series against baseball’s biggest surprise this season, the AL East-leading Tampa Bay Rays.

“We always get a lot of fans down there so it will kind of be like a home playoff atmosphere,” Jon Lester said Sunday, after pitching the Red Sox past the Toronto Blue Jays 4-3.

Scott Kazmir will try to protect the Rays’ one-game lead over Boston when he starts against Daisuke Matsuzaka. Tampa Bay is 6-0 against the Red Sox this year at Tropicana Field.

The Rays finished a 3-6 swing to Toronto, Boston and New York with an 8-4 loss at Yankee Stadium.

“It was obviously a tough road trip,” Tampa Bay manager Joe Maddon said.