Ketel Marte blasted a two-run homer and the Arizona Diamondbacks helped their playoff chances with a 6-2 win against the Chicago Cubs to complete a three-game sweep on Sunday evening in Phoenix.

Marte had two hits and two runs for the Diamondbacks (79-72), who took sole possession of the National League’s second wild card, one-half game ahead of the Cubs and Miami Marlins, who are each 78-72.

Diamondbacks starter Ryne Nelson allowed two runs and four hits in 3 1/3 innings. The rookie right-hander struck out three and walked three on 75 pitches.

Luis Frias (1-0), Miguel Castro, Ryan Thompson and Bryce Jarvis followed with 5 2/3 scoreless innings of relief.

Cubs starter Jordan Wicks (3-1) was tagged for three runs and four hits in 4 1/3 innings. He struck out five and walked four in his fifth major league start.

Ian Happ had three hits and a run for the Cubs (78-72), who have lost five in a row.

The Diamondbacks scored three runs in the first inning. Wicks walked the leadoff batter and then gave up a single to Corbin Carroll. Back-to-back fielder’s choice groundouts brought home the first run, Lourdes Gurriel Jr. delivered an RBI double, and Emmanuel Rivera hit a sacrifice fly for a 3-0 lead.

Dansby Swanson led off Chicago’s second inning with a double and scored two batters later on Mike Tauchman’s single to cut the deficit to 3-1.

The Cubs put their leadoff runner on for the third straight inning in the third on Happ’s single and loaded the bases on consecutive walks with no outs. Cody Bellinger’s double play grounder scored one run, but Gurriel ran down a long fly toward the gap by Swanson to end the inning.

Chicago reliever Jose Cuas gave up an infield single to Jordan Lawlar with one out in the sixth, and Marte lined the next pitch over the fence in left for a two-run homer that extended the lead to 5-2.

Jace Peterson RBI double in the seventh made it 6-2.