"There's no way we could have lost that game today. We weren't going to let it happen," right-hander Sergio Romo said. "You could see it in my teammates' eyes and in the way we played. We wanted to win this game and we wanted it bad."
Ishikawa contributed by doubling and scoring the tying run in the seventh inning on a wild pitch before breaking the 2-2 deadlock with a three-run, eighth-inning homer off Arizona reliever Jon Rauch (2-2).
"I would say that was probably the biggest hit I've had so far," said Ishikawa, who's still technically a rookie despite stints with the Giants in 2006 and 2008.
The D-backs nearly upstaged Ishikawa in the ninth. Rallying with two outs and nobody on base against Brian Wilson, who threw 41 pitches in 2 2/3 shutout innings Monday, Arizona scored twice and had runners on second and third. Romo relieved the weary Wilson, who had thrown 29 pitches, and retired Chad Tracy on a grounder to second base to end San Francisco's three-game losing streak.
Though the Giants remained four games behind Colorado in the National League Wild Card race, the sense of relief in their clubhouse was almost palpable.
Said Romo of the victory, "It's going to lift our spirits big-time and should give us momentum going into tomorrow and the rest of the series."
Right-hander Matt Cain, who yielded two runs (one earned) and four hits in seven innings, said that this effort "really shows the heart of what these guys are about."
All that heart might have meant nothing without Ishikawa's muscle. Limited to part-time duty at first base by Ryan Garko's arrival before the Trade Deadline, Ishikawa entered the game with only one extra-base hit in his previous 68 at-bats spanning 31 games.
But manager Bruce Bochy, intending to start the right-handed-batting Garko on Wednesday against Arizona left-hander Doug Davis, opted for the left-handed-swinging Ishikawa against Dan Haren, the D-backs' ace right-hander.
Bochy also considered Ishikawa's uncanny production at AT&T Park.
"For some reason, he hits well here and feels comfortable here," Bochy said after Ishikawa lifted his home batting average to .353 with seven home runs and 25 RBIs in 46 games.
With Arizona leading, 2-1, the Giants pulled even in the seventh as Ishikawa drilled a leadoff double to deep center field, moved to third as first baseman Brandon Allen mishandled Juan Uribe's grounder and scored one out later as Haren flung a wild pitch.
Since pinch-hitter Pablo Sandoval was batting at the time, Ishikawa was ready for anything, such as a wicked pitch in the dirt.
"We know that [Haren] has that good splitter and that good slider," Ishikawa said. "I figured, too, with Pablo at the plate, they're going to try to maybe pitch around him a little bit, throw a lot of offspeed."
One inning later, Rauch walked Nate Schierholtz and Fred Lewis with one out. Up came Ishikawa, who hoisted an 0-1 fastball onto the right-field arcade for his ninth homer of the season.
"I didn't get all of it," Ishikawa said. "I knew I hit it well; I was just kind of praying that it would either hit off the wall or get over the head of the outfielder to get the run in."
The rest was up to Wilson, who almost certainly will be unavailable Wednesday, and Romo, who'll likely substitute as closer again if the Giants need to preserve a late lead.
"The possibility of being next in line gives me confidence," said Romo, who has converted both of his save chances this year. "I'm not afraid of the opportunity to close a game. ... I didn't feel nervous or anything. I knew if I threw the pitches I'm capable of making, we'd come out on top."