SAN FRANCISCO -- Diluting the intoxicating hype swirling around Brandon Belt, Giants general manager Brian Sabean said Thursday that he foresees the club's top prospect beginning the season at Triple-A Fresno.

All offseason, Sabean and other Giants officials have touted Belt as a possible Opening Day starter at first base or left field. Sabean finally tempered those expectations.

"You don't want a young player, or potentially a player that's going to burst on the scene, [coming] to Spring Training and [having] no chance," Sabean said. "You have to give them some hope that you're going to be open-minded. Having said that, I probably expect him to start in Triple-A, and we'll be conservative. But you can't kill his enthusiasm or his will to want to make the team. He'll have to force his way into this mix through his performance."

The Giants' enthusiasm for Belt hasn't dwindled at all. As Sabean said, "There's too many educated opinions, inside and outside the organization, that he's going to be a front-line player."

In fact, Buster Posey, Belt's immediate forerunner as San Francisco's premier prospect, opened last season at Triple-A before being recalled on May 29. He proceeded to win the National League Rookie of the Year Award.

The Giants want to be certain that Belt is thoroughly ready for the Major Leagues before they fit him for a San Francisco jersey. The 22-year-old generated raves in 2010, his first professional season, by hitting .352 with 23 home runs and 112 RBIs at three Minor League classifications. But he struggled somewhat at Triple-A, where he batted .229 in 13 games.

"If Belt comes to the big leagues, we want to make sure that he's able to stay and contribute," Sabean said. "If he's going to be a role player or we have to overmanage him to protect him, then he belongs in Triple-A."