Scottsdale, AZ (SportsNetwork.com) - The defending World Series champion San Francisco Giants will be without a key regular for perhaps the first month of the 2015 season after All-Star outfielder Hunter Pence fractured his left forearm in Thursday's spring training game.

Pence was struck in the wrist by a pitch from Chicago Cubs hurler Corey Black in the sixth inning of San Francisco's 8-6 Cactus League win. The Giants announced after the game that the energetic right fielder sustained a non- displaced fracture of the ulna bone and will be sidelined between 6-to-8 weeks.

The Giants open the regular season at Arizona on April 6.

Pence had played in all 162 games for the Giants in each of the last two seasons and has missed just two over the last three.

Since joining San Francisco in a midseason trade with Philadelphia in July of 2012, Pence has helped the Giants to a pair of World Series titles and has averaged 24 home runs and 86 RBI over the past two seasons.

The 31-year-old earned his third career All-Star selection in 2014 and ended the campaign with 20 homers, 74 RBI, 13 stolen bases and a .277 average. Pence then hit .444 (12-of-27) with seven runs scored and five RBI during San Francisco's seven-game victory over Kansas City in last October's Fall Classic.