The Philadelphia Union are into the MLS is Back Tournament semifinals thanks to a 3-1 win over Sporting Kansas City on Thursday night that included a Sergio Santos brace.

Head coach Jim Curtin’s group will face either the Portland Timbers or NYCFC next Wednesday, with their opponent determined after Saturday’s nightcap quarterfinal matchup (10:30 pm ET | FS1, TUDN, FOX Deportes in US; TSN in Canada).

After a stale opening portion, the Union blitzed Sporting for three goals in 15 minutes. It all started when Jamiro Monteiro made it 1-0 in the 24th minute, tapping home after Alejandro Bedoya squared across goal with the defense split open.

The Union quickly doubled their advantage in the 26th minute on Santos’ first of the evening. He latched onto SKC defender Luis Martins’ poor back pass after an attacking free kick, then bursted 80 yards before chipping over Tim Melia for the 2-0 lead.

Santos found his second in the 39th minute, brushing home with his left foot after a brilliant Brenden Aaronson turn in midfield. The US men’s national team prospect let the ball run across his body, then slipped his teammate through for the 3-0 advantage.

Sporting weren’t dealt a knockout blow, though, and they scored just before halftime via Alan Pulido’s header. The Mexican No. 9 drifted to the back post in stoppage time, and powerfully headed home Johnny Russell’s cross.

Head coach Peter Vermes brought on all five substitutes in search of a comeback, but Union goalkeeper Andre Blake produced six saves to continue to his impressive form.