Former Spain international Vicente fired Brighton to within two points of the play-offs as Hull missed the chance to go second.
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The 31-year-old midfielder has struggled with a constant stream of injuries since Seagulls boss Gus Poyet persuaded him to move to the south coast 18 months ago after 11 years with Valencia.
But when he does get on the pitch, Valencia is a class act and he proved it by climbing off the bench to grab Brighton's 83rd-minute winner with a free-kick, his first goal of the season.
Hull needed only a point to climb into the automatic play-off spots and would have grabbed all three themselves but for some fine second-half saves from Tomasz Kuszczak.
Tigers goalkeeper David Stockdale was also busy in a first half dominated by Brighton.
Spanish full-back Bruno linked up well with Craig Mackail-Smith to tee up Dani Lopez for a shot which Stockdale got down well to palm away at full stretch.
Stockdale also had to tip a fierce free-kick from Andrea Orlandi over the crossbar, while Bruno's cross was headed wide by Leonardo Ulloa.
Hull showed more attacking ambition after the break and Brighton's on-loan Stoke defender Matt Upson had to make a brave defensive header to stop Jack Hobbs getting on the end of Ahmed Elmohamady's dangerous cross.
Jay Simpson headed a Robbie Brady cross wide at the near post and Robert Koren prodded Stephen Quinn's centre over the crossbar.
David Meyler should have done better with another inviting cross from Brady but he sidefooted his effort across goal and wide.
Vicente's arrival sparked Brighton into life and they should have gone ahead in the 67th minute when the substitute's superb reverse pass sent Wayne Bridge to the byline.
Bridge crossed towards Ulloa and the ball was only half-cleared to Orlandi as he arrived in the area, but the former Swansea midfielder's composure deserted him as he blazed over the top.
Brady almost conjured up a stunning goal for Hull but Kuszczak got his fingertips to the dipping, 30-yard strike.
Kuszczak made another superb save to keep out Elmohamady's low drive in the 79th minute.
And the Pole's intervention proved pivotal four minutes later when Orlandi was tripped by Corry Evans on the edge of the area.
Vicente stepped up and slammed a low free-kick past the wall, under the body of the diving Stockade and into the net to secure three valuable points for the play-off hopefuls.