MLS Golden Boot winner Valentin Castellanos scored as New York City clinched a spot in the Eastern Conference semi-finals with a 2-0 home win over Atlanta United on Sunday.

Castellanos, who netted 17 regular-season goals, opened the scoring in 49th minute with a miscued volley which bounced in fortunately over Atlanta goalkeeper Brad Guzan.

Alexander Callens doubled New York City's lead four minutes later, heading in unmarked from close range after Guzan tipped Maxi Moralez's effort on to the frame of the post.

Atlanta defender Alan Franco was sent off late for dissent to rub salt into the wounds, as New York City secured a fifth semi-final berth in the past six seasons.

New York City will next play Eastern Conference top seed and Supporter's Shield winners New England Revolution.

Sebastian Blanco netted a second-half double as Portland Timbers came from behind to beat Minnesota United 3-1, clinching four consecutive wins and a Western Conference semi-final date with Colorado Rapids.

Franco Fragapane gave Minnesota an 11th-minute lead, but Portland rallied with Larrys Mabiala heading in the equaliser before half-time.

Blanco rifled in a low drive early in the second half before opening a two-goal lead with a spectacular 66th-minute long-range strike.