SCOTTSDALE, Ariz. — Travis Ishikawa was 13-years old when he began to understand the contributions a first baseman can make.

"We had a third baseman who had trouble getting the ball across the diamond," Ishikawa said. "Saving balls here and there, it built up my confidence to the point where I expect to make every play."

Ishikawa appears to be the front-runner to become the San Francisco Giants starting first baseman as spring training games begin — and his glove is one of the reasons.

"You can't rely on getting a game-winning hit every night or driving in four runs every night. What you can do, the things you can control, is how much effort you put into your defense," Ishikawa said.

"Maybe you don't drive in that couple of runs, but you maybe save a couple with your defense. I've always taken pride in giving the pitchers as well as the team the best chance to win the game."

At the same time, Ishikawa got off to a strong start at the plate in the Giants spring training opener Wednesday with three hits, two home runs and four RBIs in a 10-7 victory over Cleveland.

A left-handed hitter, Ishikawa hit a bases-empty homer off Cleveland lefty Zach Jackson in the fourth inning and broke a 3-3 tie with a two-run homer in the sixth inning off right-hander Edward Mujica.

Ishikawa showed a good bat as a September call-up last season, when he hit .274 with six doubles, three home runs and 15 RBIs in 95 at-bats while starting 26 games at first.

Converted outfielder John Bowker is another candidate at first base after making 67 starts there last season for the Giants. Rich Aurilia enters camp on a minor league contract, as a reserve at both first and third base.

All that could change if Pablo Sandoval proves to be a better fit at first base than third, where the Giants want him to play this season. But Ishikawa isn't concerned with any of that right now.

"The attitude I have taken all camp is that the job is mine to lose," he said. "I felt that going into the offseason, and I will continue to work as hard as I can to show that I deserve it and I have earned it. I'm not trying to sound cocky at all. It just gives me that confidence. You have to play with confidence.

"I'm going to continue to think the same way until they tell me otherwise. I hope I never hear that. Regardless of what happens, if they find something else for me, I'll stay humble, whether it is being a bench player, a role player. I want to be the best possible player when I get that opportunity."

Ishikawa's time does appear to have come. He put together a strong minor league season in 2008, hitting .299 with 35 doubles, three triples, 24 home runs and 94 RBIs in stops at Double-A Connecticut and Triple-A Fresno. His slugging percentage was .578.

"My game plan isn't to try to hit home runs, he said. "Just hitting the ball hard is all you can ask for. Whether it's over the fence or finds a gap, either way."

Ishikawa, a 21st-round draft choice in 2002, said he believes his seven-year climb through the Giants' system has been beneficial.

"It's definitely been an adventure. I think the biggest thing is learning and growing. I think that has matured me more than just shooting straight through the system," he said.

"I've learned that you go through those tough times and the good times, and I've learned how to handle them."