One of the hottest pitchers in the major leagues - Chicago right-hander Ryan Dempster - opens the second half of the season today when the Cubs host the Arizona Diamondbacks in the second of three weekend games at Wrigley Field.

Dempster, a 35-year-old native of British Columbia, was 0-3 though nine starts at the end of May, but was positively stellar in June and early July, winning four straight decisions against Milwaukee, Minnesota, Boston and the New York Mets.

He didn't allow a single run across those four starts - which were interrupted by a stint on the 15-day disabled list with a balky right lat muscle - while surrendering 16 hits, walking three and striking out 16 in 27 innings.

He's not given up a run since May 30, when he was touched for six runs in 4 1/3 innings while getting a no-decision in the Cubs' 8-6 defeat of the San Diego Padres.

Dempster is just 2-8 in 19 career meetings with the Diamondbacks, including 15 starts, while posting a 6.72 ERA in 83 innings.

In Friday's opener, Alfonso Soriano smacked four hits, including a pair of home runs, drove in five and scored three times, leading the Cubs to an 8-1 win.

"I swung very good. (In the All-Star break) I cleared my mind and my body, too. The game I had, I hope I have a couple of more like that," Soriano said.

Paul Maholm (7-6) surrendered a run on six hits and a walk in seven innings for the Cubs, who have won three of their last four.

Anthony Rizzo tallied two hits and scored twice.

Ian Kennedy (6-8) was shelled for six runs on seven hits and two walks in five-plus innings for the Diamondbacks, who had their three-game winning streak snapped.

"He was unable to execute his pitches, especially against Soriano," Arizona manager Kirk Gibson said.

The Diamondbacks start left-hander Joe Saunders, who returns for the first time Saturday after a stint on the 15-day disabled list with a strained left shoulder.

Saunders last pitched on June 16 in Anaheim, where he allowed eight hits and two runs in six innings of a 2-0 loss to the Angels.

He was placed on the DL the next day.

Saunders made one minor-league start for Arizona's Rookie League affiliate and allowed three hits and five runs in 4 1/3 innings.

He's dropped both career meetings with the Cubs, allowing 14 hits and seven earned runs over 8 2/3 innings.

The Diamondbacks swept a three-game series in Phoenix in June, while the Cubs won last year's season series, 4-3.

Arizona last won the season series in 2009, 4-2.