* Marco Silva's Hull earned a crucial 2-1 win over Swansea
* Sub Niasse proved Tigers' hero with a second-half double
* Mawson scored a 91st minute consolation for Swans
* Senegal international Niasse proved an inspired substitution
* Niasse, on 69 minutes, struck within six minutes of coming on
* Hull still in bottom three but jumped Middlesbrough to go 18th
* The win meant Hull are still unbeaten at home under Silva
* Hull at Everton next, while Swansea visit Bournemouth
March 11 (Reuters) - Oumar Niasse again proved Hull City's hero as he netted a superb double in the 2-1 victory over fellow strugglers Swansea City that gave a serious shot in the arm to the Tigers in their fight against relegation.
Marco Silva's Tigers had looked fairly toothless until Senegal international Niasse was introduced in the 63rd minute and it proved an inspired substitution from the Portuguese manager.
Within six minutes, Niasse had been played in by Abel Hernandez before slotting the ball beneath Łukasz Fabianski and he then sent the KCOM Stadium into further raptures with another clinical finish 12 minutes from time.
Manager Paul Clement, who has overseen Swansea's remarkable recent resurgence, suffered a miserable afternoon as he lost his top scorer, Spanish international Fernando Llorente, to injury and then had to watch Alfie Mawson's injury-time goal count as a mere consolation.
Hull, relieved to survive a nervous final couple of minutes after Mawson's header, were still left in the bottom three but their victory saw them leapfrog Middlesbrough into 18th place and move to within three points of Swansea.
The fortunes of the two teams with the worst defensive records in the league had been boosted since the turn of the year when they brought in their new managers in January just two days apart.
Yet it was still Silva who was in more urgent need of the points than Clement -- and Niasse, who has made a striking impact since being brought in on loan in January from Everton where he struggled to make an impact, illustrated his worth in the space of nine second-half minutes.
With Hull seemingly struggling for ideas and inspiration, Silva gambled by bringing him on to double his striking options in place of midfielder Alfred N'Diaye.
In this revamped tactical line-up, the man who has already scored for the Tigers against Manchester United in the League Cup and Liverpool in the league quite changed the complexion of the match.
First, Niasse demonstrated cool skill to beat Fabianski before a sharp close-range finish from fellow substitute Ahmed Elmohamady's cross effectively sealed the points.
There were a few fingernails being chewed by the home fans in the dying seconds after Swansea defender Mawson headed home from Gylfi Sigurdsson's free-kick but the win brought huge relief to Hull, who had won just one of their previous six league matches.
Silva made two changes from the defeat by Leicester City with Hernandez and Omar Elabdellaoui brought in for Niasse and Elmohamady.
Clement was forced to make two changes in the first half as both Angel Rangel and Llorente succumbed to injuries but with the exception of their lively Polish winger Kamil Grosicki, who created a couple of chances just before the break, Hull rarely threatened.
After the break, the most glaring opening was blazed over the bar by Wayne Routledge before Hull finally awoke with the introduction of Niasse. (Reporting by Ian Chadband; Editing by Rex Gowar and Pritha Sarkar)