This will be Hansen's second taste of the big leagues after last season becoming the first player in Red Sox history to reach the Majors in the year he was drafted. He made his Major League debut on the night he was promoted -- Sept. 19, at Tampa Bay -- and pitched a perfect fifth inning.
"It would've been great if we had come out on top," Hansen said of his whirlwind day, which ended by watching a 2-1 Sox loss. "It was a hard-fought [game]. I definitely think I am [ready]. I developed a changeup down in the Minor Leagues, and I feel that's one of the pitches that's going to help me out throughout my career."
Keith Foulke's ailing back, combined with Monday's loss -- in which they had to use Van Buren in the second inning -- forced the Red Sox to deepen their bullpen, as rookie David Pauley made just his second big-league start on Tuesday.
"Because we didn't know about Foulke's availability, we needed to protect ourselves a little bit," skipper Terry Francona said. "Van Buren had pitched so much, he obviously wasn't available, and [David] Riske wasn't available. We had gone back and forth on what to do and who to have ready if something happened, so we just needed to protect ourselves a little bit."
Hansen's specific role has yet to be determined.
"I don't know if we have it defined," Francona said. "Some of it will be on needs and how the games go. We'll see."
Hansen finished 2005 with a 6.00 ERA in four relief appearances for Boston.
His development has accelerated this season, with the addition of a changeup to go along with a fastball in the high 90s and a devastating slider. Though he is debuting as a reliever, he is seen as a potential starter.
"I'm definitely more confident now with a changeup," Hansen said. "I was able to throw it in different situations -- 3-0 count, 3-1 count, that's where you want to be with all your pitches, to be able to throw them in any count you want."
This year, the 22-year-old has combined for a 1-2 record and 2.08 ERA in 12 games (four starts) with Double-A Portland of the Eastern League and Pawtucket.
Hansen started the season in Portland, going 1-0 with a 0.82 ERA in five relief appearances. He began the year by pitching 10 scoreless innings for the Sea Dogs before allowing a run on April 24. That was the first run he surrendered in his Minor League career, a span of 22 2/3 innings over two seasons.
Promoted to Pawtucket on April 27, Hansen is 0-2 with a 2.66 ERA in seven games (four starts) for the PawSox. He made his last four outings as a starter, and posted a 2.30 ERA in those games. Overall, he has allowed a run in three of seven appearances with Pawtucket while holding the opposition to a .224 batting average.
Van Buren is 1-0 with a 6.23 ERA in five relief appearances over two stints with the Red Sox in 2006. He was most recently recalled on May 24 and had a 7.94 ERA in four games since that time.