PHOENIX -- Adam Dunn had no idea the Cincinnati Reds were about to trade him to the Arizona Diamondbacks on Monday.

But with longtime teammate Ken Griffey Jr. already gone and the Reds on a six-game losing streak, Dunn didn't mind packing his bags and heading West.

"It was one of those pleasant surprises," the slugger said on a conference call. "To come off the terrible month that we had in Cincinnati, and you get a phone call today saying you're being traded to a first-place team. As a player that's all you could ask for."

Dunn, who was tied for the big league lead in homers, could boost an Arizona offense that was ranked 20th in the majors in runs scored. The Diamondbacks (60-58) entered the day with a 1½-game lead in the NL West over the Los Angeles Dodgers, who recently traded for Manny Ramirez.

Arizona sent minor league right-hander Dallas Buck to Cincinnati (52-67) along with two players to be named. The 23-year-old Buck was 1-4 with a 3.94 ERA at Class-A South Bend.

Dunn, 28, was batting .233 for the Reds with 32 home runs and 74 RBIs. He has a good eye at the plate (80 walks) but also strikes out a lot (120 Ks).

Dunn has a .247 career batting average with 270 homers and is eligible for free agency at the end of the season.