PHOENIX, July 24 (UPI) -- Reed Johnson's grand slam homer finished off a six-run eighth inning Wednesday and gave the Chicago Cubs a 10-6 victory over Arizona.

Chicago avoided a three-game sweep and maintained a one-game lead over the charging Milwaukee Brewers in the National League Central.

Johnson's homer gave Chicago a 10-3 lead and provided enough cushion to survive a three-run shot by Chris Snyder in Arizona's eighth.

The Cubs were also heartened by the return of outfielder Alfonso Soriano, who had been on the disabled list since June 11 with a broken finger. Soriano had a hit and an RBI in five at-bats.

Ted Lilly (10-6) got the win, giving up three runs on six hits in six innings. Doug Davis (3-5) allowed four runs on five hits in seven innings.

With Arizona trailing by only a run going into the eighth, Micah Owings walked Ryan Theriot to open the inning. Aramis Ramirez singled with one out and Geovany Soto singled in Theriot. Kosuke Fukudome walked to load the bases and Mark DeRosa also walked to force in a run.

Leo Rosales relieved Owings and faced Johnson, who promptly hit a 1-0 pitch over the wall in right.