Southampton midfielder Dusan Tadic praised their spirit for victory over FA Cup opponents West Brom.
Tadić added to Wesley Hoedt's first-half strike with a delightful dink over Ben Forster to make it 2-0. But Salomon Rondon pulled a goal back for the Baggies.
Saints then stood up to a physical battle from the hosts late on to secure their passage.
“We are very happy because we showed great character to fight against a physical and strong team, especially in the second-half," Tadić reflected.
“It was very important to get an early goal. I think from the started we had a control on the game.
“In the second-half it was a little bit difficult because they played direct and you need to defend against that. We showed we can do that."