Middlesbrough boss Gareth Southgate was facing up to a third FA Cup replay of the season, after seeing his side held 2-2 at home by West Bromwich Albion in round five.
Boro have already needed two attempts to see off Hull City and Bristol City and will face a tough test of their mettle at The Hawthorns.
Southgate said: "We were deservedly ahead at half-time, but in the second half we tended to sit back a little and allow them back into the game.
"West Brom are playing with a lot of confidence. Credit to them, they played very well. They had nothing to lose in coming here.
"My players are disappointed because they expect a Premier League team to win at home. West Brom, though, are a Premier League team in all but name.
"It will be a big challenge at West Brom, but we have had our share of replays over the past two seasons.
"We have had plenty of replays, so I suppose the chairman should be happy. But we need to get through to keep him really happy."