Swansea suffered their first loss under new coach Francesco Guidolin to stay mired in relegation trouble after a tepid display against Southampton at the Liberty Stadium on Saturday. The first half was devoid of excitement and the second was equally dull until the visitors took the lead when Shane Long turned in James Ward-Prowse's cross with 20 minutes left. Swansea had a loud appeal for a penalty turned down when Alberto Paloschi tumbled in the area. "When I arrived the table was worse, but the table is still not good," Italian Guidolin, who had overseen a win and two draws in his last three games, told reporters. "I'm disappointed. We prepared well for this match, but for the first time in my five matches, my team didn't play well." Southampton remained relatively untroubled as they completed a double over Swansea and extended their unbeaten league run to six games to move into sixth place. "Even in difficult periods in the game we are looking sure about ourselves," Southampton manager Ronald Koeman said. "We don't make stupid mistakes at the moment and we keep believing we can score."