Ronald Koeman heaped praise on Shane Long after the striker scored on his 50th Southampton Premier League appearance to seal a 1-0 victory at Swansea City.
Long's second-half header was the difference between the sides at the Liberty Stadium, with Southampton's sixth successive clean sheet ensuring they recorded their fifth win in six matches.
The Republic of Ireland international has kept his place in the Southampton team despite the signing of Charlie Austin and Koeman pinpointed Long's work rate as the reason why he is in the side.
"I think he deserves to start because he is working hard," said Koeman.
"He is always on the move, he is always running, he's very dangerous - and that's the reason why every time I start with Shane.
"We know with the signing of Charlie we have big competition.
"I had Charlie, I had [Dusan] Tadic, I had [Sadio] Mane on the bench, but that's really what we like to have because a strong squad makes progress and competition easier, even if some decisions to make are very difficult."
Koeman also highlighted his team's defensive performance, noting it is "not normal" to keep six successive clean sheets.
"We are working hard, we have good defensive organisation, it's difficult to create open chances against us - we saw that [on Saturday]," he said.
"The team is looking very comfortable."
Southampton climbed to sixth place and Koeman said: "If Leicester can win the title, we can be fourth or fifth in the league because really it's a tough competition.
"We know our situation and we are happy about our position in the table and we know there are still 12 games to go."
