After coming off the bench in the bench in Brighton's narrow win over Leeds United, Bafana Bafana star Tau was reinstalled in the line-up, with the likes of Leandro Trossard and Neal Maupay rested on the bench.
The game was open in the early stages and Luke Garbutt gave the Seagulls a scare in the 18th minute with a strike from outside the box towards the top corner that was saved by shot-stopper Christian Walton.
Yves Bissouma settled the nerves for Graham Potter's charges just before the half-hour mark after breaking the deadlock with a strike from outside the box that found the top corner.
However, Gary Madine equalised for the visitors in first-half stoppages with a close-range finish after a cross by Garbutt.
Blackpool were giving as much as they got coming from the break but Steven Alzate restored the lead for Brighton just before the hour-mark with a strike from outside the box after he was teed up by Alexis Mac Allister.
Three minutes after going ahead, Potter withdrew Tau and brought on Maupay while Trossard came on for Allister in a double-change.
The Seagulls were managing the game in the closing stages, denying the third-tier side chances to come back into the game and they held on to book their place in the fifth round while Blackpool crashed out of the tournament.
