Brighton looked on course for the quarter-finals after Leonardo Ulloa scored his third goal in as many matches with a beautifully taken finish.
But as Brighton sat back to defend their lead with just minutes remaining, Sagbo turned in Sone Aluko’s cross.
The promotion-chasing Championship side had their own woodwork keep out Sagbo midway through the first half. But the home side then went ahead with a moment of Premier League quality from Ulloa, the striker latching onto Will Buckley’s pass to lift over the advancing Allan McGregor.
Hull were again denied by the woodwork as Curtis Davies headed against the bar before Ulloa missed a great chance to put Brighton further ahead right before the break, nodding wide from Buckley’s cross.
Chances were scarce in the second half but Hull made the most of their first effort on target to draw level and almost snatched it right at the death as Jake Forster-Caskey cleared David Meyler’s header off the line from Tom Huddlestone’s corner.
26’ – SAGBO HITS THE WOODWORK: It’s a great cross from Elmohamady and Sagbo hits the crossbar with Brezovan beaten and it cannons away to safety.
30’ – BRIGHTON TAKE THE LEAD: Great work from Ulloa as he latches onto Buckley’s pass, beats the defence and flicks it nicely past McGregor.
31’ – DAVIES HITS THE BAR: Again the visitors are denied by the woodwork as Davies heads against the bar direct from the corner.
45+2’ – ULLOA MISSES GREAT CHANCE: Brighton should be 2-0 up as Ulloa only has to direct his header in but it’s wide from Buckley’s accurate cross.
85’ – SAGBO DRAWS BRIGHTON LEVEL: He steals in to divert Aluko’s cross past Brezovan.
90+3’ – GREAT BLOCK FROM DUNK: He stretches out a leg to divert Koren’s goalbound effort over for a corner.
90+4’ – CASKEY SAVES BRIGHTON: It’s another great clearance off the line from Meyler’s header as Brighton hold on.
Ulloa has scored in Brighton’s last three home games
Brighton have now faced Hull three times in the FA Cup, winning twice in Round Three in 1985 and Round Four in 1986 before tonight’s draw.
Hull have still only one once in 24 visits to Brighton and that was back in 1963.
Hull have lost just one of their last 13 matches in the FA Cup against teams from a lower division, winning eight and drawing two.
TALKING POINT: Hull denied by the woodwork. In a game of few chances, Brighton are still in the Cup thanks to a matter of millimetres that denied both Yannick Sagbo and Curtis Davies. In fact there were only three chances on target in the entire match and two ended in goals.
MAN OF THE MATCH
Leonardo Ulloa (Brighton): Has now scored in Brighton’s last three matches and looked to have scored another winner until Sagbo’s late equaliser. Excellent all-round performance.
Brighton: Brezovan 6; Calderon 7, Upson 7, Dunk 6, Chicksen 6; Ince 6, Foster-Caskey 7, Andrews 6; Buckley 6, LuaLua 6, Ulloa 8. Subs: March 7, Obika 6.
Hull City: McGregor 6, Figueroa 6, Davies 7, Huddlestone 6, Koren 7 , Livermore 6, Sagbo 7, Faye 6, Aluko 7, Elmohamady 5, Quinn 6. Subs: Meyler 6, Boyd 6, Fryatt 6.
MATCH IN A TWEET