CHICAGO -- The Chicago Cubs claimed a rain-shortened, 2-0 victory over the San Francisco Giants early Wednesday morning.

The Giants might protest to get the game restarted.

A surprise storm that hit in the fifth inning Tuesday night and difficulty by the grounds crews to fully cover portions of the infield created soggy and dangerous conditions.

The umpires finally called the game after 4 1/2 innings and a 4-hour, 34-minute delay.

"We did everything we could, we waited a long time," Cubs manager Rick Renteria said. "There was a lot of moisture in there, and the one thing everybody has to be cognizant of is that you don't want any of those guys to get hurt, period."

Cubs first baseman Anthony Rizzo went 2-for-2 with a two-run home run in the first inning that stood up as the game-winner.

An intense 15-minute downpour halfway through the fifth inning led to the lengthy delay, and repeated attempts were made to restore the field before the contest was finally called at 1:16 a.m. CT and declared an official game.

"It's a long, frustrating night," Giants manager Bruce Bochy said, who added that the Giants likely will protest the game to Major League Baseball. "I don't know what other recourse we can take. It's a tough night for everybody."

The Cubs' grounds crews had difficultly covering the left side of the infield, leading to drenched dirt and more extensive work in an unsuccessful attempt to make it playable.

"The field was in bad shape here. It wasn't quite playable," Bochy said. "A 15-minute rain there and we couldn't get the tarp on in time, and in this day and time, that's something should have been done a little bit more."

Renteria and Bochy inspected conditions with umpires at 10:25 p.m. They were back out an hour later checking out an improved infield that apparently was still soggy in spots.

Little work was done over the next 90 minutes, and the infield tarp remained open in right field while Bochy reappeared to check the infield just before 1 a.m.

Umpires emerged at 1:10 a.m. to probe various infield spots and finally called the game.

The Cubs (55-70) won their third consecutive game while the Giants (65-59) saw a two-game winning streak snapped. San Francisco slipped 4 1/2 games behind the first-place Los Angeles Dodgers in the National League West.

Cubs left-handed starter Tsuyoshi Wada (3-1) worked five shutout innings and allowed six hits and no walks while striking out three.

Giants right-handed starter Ryan Vogelsong (7-9) gave up two runs on three hits in four innings. He walked two and struck out four.

Rizzo gave the Cubs a 2-0 lead in the first inning with a home run to right than landed on Sheffield Avenue. Rizzo's team-leading 29th homer came on a 2-0 pitch and drove in second baseman Javier Baez, who was on base after a walk.

Cubs general manager Jed Hoyer said he expects the field should be back in playable condition for Wednesday night's second game of the three-game series.

NOTES: Giants manager Bruce Bochy confirmed that C Hector Sanchez sustained another concussion Saturday during a rehab assignment at Triple-A Fresno and is out for the foreseeable future. ... San Francisco OF Michael Morse saw his streak of recording a hit in seven consecutive at-bats and reaching base in each of his last nine end when he struck out to open the second inning. He finished 0-for-2 with two strikeouts. ... Giants RHP Jake Peavy (1-3, 3.86 ERA) will face Cubs RHP Edwin Jackson (6-13, 5.74 ERA) Wednesday. ... Cubs SS Starlin Castro is one homer away from matching his single-season career high. He hit his 13th on Sunday against the New York Mets, a game-winning solo shot. ... Sunday's 4-1 victory over the Mets was the fourth consecutive game in which the Cubs allowed four hits. The Giants managed six hits against Chicago on Tuesday. In the past 100 years, the Cubs have not allowed four or fewer hits in five straight games.