Lukaku keeps Everton top-four challenge on track
Everton's Belgian forward Romelu Lukaku (C) shoots wide during the English Premier League match against Southampton at Goodison Park in Liverpool, northwest England on December 29, 2013
Roberto Martinez's side had taken an early lead through Seamus Coleman before Southampton threatened to steal a point thanks to a Gaston Ramirez strike midway through the second half at Goodison Park.
But Lukaku, on loan from Chelsea, netted his ninth club goal of the season with 16 minutes to play to give Everton their third win in four matches.
As a result, the Toffees moved above Liverpool into fourth place, although their Merseyside rivals can reclaim that spot with a draw or win at Chelsea later on Sunday.
Martinez made five changes to his starting line-up from the surprise loss against Sunderland on Boxing Day, with England left-back Leighton Baines returning after a broken toe.
Captain Phil Jagielka was missing due to a hamstring injury, so defender Antolin Alcaraz came in for his Toffees debut.
Goalkeeper Tim Howard and midfielder Gareth Barry were also absent due to suspension, so Joel Robles made his first Everton Premier League start in between the posts.
Everton certainly looked no weaker than usual in the early stages as Coleman's third goal in four games fired them into the lead in the ninth minute.
The Republic of Ireland international collected the ball from Leon Osman, advanced down the right flank and then cut into the box, beating James Ward-Prowse in the process, before driving a powerful shot beyond Kelvin Davis.
In the 18th minute, Steven Naismith chased a long ball over the top and, as Davis caught it, the Everton forward went to ground in the area having felt contact from Dejan Lovren, but no penalty was given.
Having juggled the ball into space on the edge of the area, Southampton's Adam Lallana dragged a shot wide and Ward-Prowse looped another effort off-target.
Southampton drew level in the 71st minute as Ramirez collected the ball from Lallana and sent a dipping effort goalwards that seemed to elude Spanish goalkeeper Robles too easily on its way into the net.
Robles will have surely been relieved to have seen Everton's advantage restored three minutes later.
Having received the ball from substitute Steven Pienaar as the Toffees swept forward, James McCarthy neatly set up Lukaku, who smashed home past Davis from 12 yards.