Leicester manager Claude Puel experienced a comfortable victory on his return to former club Southampton thanks to two goals from striker Shinji Okazaki.
Puel was sacked by the Saints in June after just one season in charge, having guided the club to eighth place and the League Cup final.
The Frenchman, who took over at Leicester in October, did not hide his emotions as the Foxes claimed their fourth consecutive win in style.
Leicester took an early lead at St Mary’s with a fine individual goal from Algeria winger Riyad Mahrez, who cut in from the left before striking a low powerful shot into the corner of the net.
Japan international Okazaki added a second just after the half-hour mark, pouncing from close range after Southampton failed to clear a shot from Christian Fuchs following a corner.
Puel’s side were three goals ahead by half-time when defender Harry Maguire crossed for midfielder Andy King to tap in at the back post.
Southampton, much improved after the break, pulled a goal back after an hour through defender Maya Yoshida, who climbed highest in the six-yard box to head in Ryan Bertrand’s corner kick.
But the visitors blunted any hopes of a Saints comeback when Jamie Vardy’s cross picked out strike partner Okazaki’s brilliant run and he finished emphatically, BBC reports.