The Rockies now try to complete their first three-game sweep of the Giants in six seasons, but they'll have struggling right-hander Juan Nicasio going Sunday against one of the NL's top pitchers, Madison Bumgarner.Colorado (33-35) used Brandon Barnes' two-run, inside-the-park homer off San Francisco closer Sergio Romo in the ninth inning Saturday for a 5-4 victory. In Friday's opener, the Rockies got five runs off Romo in the ninth for a 7-4 win.Tulowitzki, batting a major league-best .355, started Friday's rally with a single but was limited to a pinch-hit appearance Saturday because of an ailing right toe."When we get the green light and he passes all the tests, he'll play," manager Walt Weiss told the team's website. "We're always going to be cautious with guys coming off an injury."Colorado, batting .337 with 40 runs in its last five games, hasn't swept a three-game series of the Giants (43-26) since Sept. 23-25, 2008, at AT&T Park. The Rockies entered this series having lost 15 of 18 in San Francisco.Colorado, though, will send out Nicasio (5-5, 5.70 ERA) after one of the worst outings in the majors this season. Nicasio allowed a career-high 10 runs and 11 hits in 3 2/3 innings in Tuesday's 13-10 loss to Atlanta, the Rockies' most recent defeat.He had a rough first inning, giving up seven runs and seven hits and was nearly hit in the head by a Justin Upton line drive."I didn't worry about that line drive to me," said Nicasio, who is 0-3 with a 14.49 ERA and 2.49 WHIP in his last three starts. "I didn't do my job. I feel bad for my team. They scored 10 runs. I need to win this game, you know?"Nicasio was 2-0 with a 1.23 ERA in his final four starts against San Francisco last season, and will likely need to be at his best again when he opposes Bumgarner (8-4, 2.67).The Giants left-hander has a 1.24 ERA in his last four starts but had a streak of six winning decisions snapped with a 2-1 loss to Washington on Tuesday. Bumgarner gave up two runs in seven innings in one of his NL West-leading club's five losses in the last six games."Usually when you pitch a game like that, you've got a pretty good chance of winning. It didn't work out our way," Bumgarner said.In an attempt to move into a tie for the NL wins lead, Bumgarner tries to win a fifth consecutive home start against Colorado. He had a 1.45 ERA in the first three of those matchups before giving up four runs in six innings in his only one this season, a 6-5 win April 11.Bumgarner, 4-1 with a 2.06 ERA in seven career home meetings, is 1-1 with a 4.05 ERA in his three overall starts against Colorado this season and has given up a season-high nine hits in two of those games.Barnes has an MLB-best five hits off Bumgarner this year in 12 at-bats. Josh Rutledge is 3 for 3 against him this season, and Tulowitzki has a homer and a double in six at-bats.Brandon Crawford, batting .341 with 11 RBIs in 12 games this month, is 5 for 13 (.385) with four doubles lifetime against Nicasio.