Ryan Dempster extended his scoreless innings streak to 27 in his first start in three weeks, Starlin Castro hit a three-run homer and the Chicago Cubs beat the New York Mets 7-0 Sunday.

Dempster (4-3) was activated from the disabled list then pitched five innings of four-hit ball in his first outing since June 15, when he experienced tightness in a back muscle. His lengthy string of zeros is the Cubs' best for a starter since Ken Holtzman went 27 innings in 1971.

The Cubs made it as comfortable as possible for Dempster, scoring four runs before he even threw a pitch.

Alfonso Soriano had an RBI single, Jeff Baker a run-scoring double and Geovany Soto drove in two runs with a single against Jonathon Niese.

Niese (7-4) had only given up four or more runs in a game five times — 16 starts — this season entering Sunday.

The Cubs finished the first half in the midst of a modest surge, winning nine of 13 to improve to a disappointing 33-52 in Theo Epstein's first year in charge.

The Mets had a chance to move a season high-tying eight games above .500 but continued a recent trend of trading wins and losses. They go into the All-Star break 46-40. New York finished a homestand against last place teams, Philadelphia and Chicago, 3-3.

Not that the Mets didn't have had their chances Sunday. They put runners in scoring position in each of first three innings and also in the sixth but came up empty.

Dempster put his streak in jeopardy by allowing a one-out triple to Scott Hairston in the second but he got Jordany Valdespin to line out to second and Josh Thole to groundout to shortstop. Niese and Ruben Tejada opened the third with singles but the Nos. 2-3-4 hitters couldn't capitalize.

After Tejada's hit, Dempster retired nine in a row before being lifted. The right-hander is scheduled to start the Cubs' first game after the All-Star break on Friday.

Dempster has won four in a row after an 18-start winless streak dating back to Aug. 11. He struck out four and walked none.

Paul Maholm came on in relief for the first time. He made 201 consecutive starts until he entered in the sixth and gave up two hits. But the Mets failed again with runners. Ike Davis popped to shortstop and Lucas Duda grounded into a double play.

Manuel Corpas, James Russell and Shawn Camp finished the eight-hitter.

Niese had settled in after the first, allowing only one hit until Luis Valbuena singled with one out in the seventh. Reed Johnson singled with two outs and Castro hit the first pitch for a three-run homer, his seventh long ball this year.

Niese allowed seven runs and nine hits in seven innings.