After a stirring hand from the crowd, Kennedy, who has been in office since 1962, exited the cart and was greeted with a handshake from Red Sox manager Terry Francona.
They then moved toward the mound, where Kennedy threw a ceremonial first pitch to Rice. After the first one hopped before reaching Rice's glove, Kennedy light-heartedly came back for take two and threw a short strike to Boston's once star slugger.
"That was an honor," said Francona. "That was a highlight. I've been pretty fortunate here to get to do some pretty neat things, and that was one of them."
Kennedy was diagnosed with brain cancer in May 2008 and returned to his office on Capitol Hill six months later.
"He's been a big public servant for this area," said Red Sox third baseman Mike Lowell. "I think he deserved the ovation he got."
There were some other unique aspects to the festivities. When the Red Sox players were announced during pregame introductions, each one emerged though the crowd, walking through the grandstand aisles between sections 15 and 25. This gave fans a chance to exchange high fives or handshakes with the likes of Dustin Pedroia, David Ortiz, Kevin Youkilis and John Smoltz as they walked by.
"I was just afraid I was going to slip and fall," Pedroia said. "I had my cleats on. It was a little different, but it was fun. It was exciting to be around the fans to see the passion they bring."
The presentation of colors was made by representatives of all five branches of the United States armed forces.
The national anthem was performed by maestro Keith Lockhart and members of the Boston Pops along with the Tanglewood Festival chorus.
At the conclusion, there was a flyover performed by four F-15 tactical fighter jets from the 104th fighter jets from the 104th fighter wing of the Massachusetts Air National Guard.
Johnny Pesky, the Red Sox icon who had his No. 6 retired last September, then grabbed a microphone and roared "Play Ball" to the delight of the packed house.
The action carried right over into the early portion of the game, with Red Sox ace Josh Beckett registering two strikeouts in the top of the first and Pedroia, the reigning American League Most Valuable Player, drilling a solo homer into the Monster Seats in the bottom of the inning.
The Red Sox went on to defeat the Rays, 5-3.
"It's exciting," Pedroia said. "My first two years were on the road. It was exciting to be in front of the Fenway fans. You're definitely nervous. You want to get off to a good start and win."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.