Wolves beat Reading 4-2 on penalties after a dramatic 1-1 Carabao Cup draw that saw the home side have two players stretchered off and finish with 10 men.
Debutant Bruno Jordao put Wolves ahead but was carried off injured before half-time after a challenge with Charlie Adam.
Lucas Boye headed Reading level in the ninth minute of time added on after substitute Meritan Shabani - another Wolves debutant - had also left the field injured.
In the shootout, captain for the night Ruben Neves, Jesus Vallejo, Ryan Bennett and Ruben Vinagre kept their nerve to score for Wolves, while John Swift's effort was saved by John Ruddy and Boye ballooned over the bar.
With Jordao and Shabani off and all three substitutes used, Wolves ended the game with 10 men.
Oxford accounted for West Ham, who made made nine changes and paid for it it as they were embarrassed 4-0, with goals from Elliott Moore. Matty Taylor, Tarique Fosu-Henry and Shandon Baptiste in the second half.
Max Power's ninth-minute long-range strike gave Sunderland a 1-0 victory over top-flight opponents Sheffield United, who made 10 changes.
Last season's beaten semi-finalists Burton continued their love affair with the competition by winning 2-0 at home to the Premier League's fifth-placed team Bournemouth, who also made 10 changes.
Oliver Sarkic put them ahead in the 14th-minute and Nathan Broadhead's late goal secured victory over a team 52 places above them in a match affected by power failures which caused a 28-minute delay.