Long, who had missed a similar chance to the one he later scored just before half time, headed home James Ward-Prowse’s cross to seal another three points for Saints.
And manager Koeman was pleased with the striker’s industrious display in the win in Wales.
“I’m very pleased with him because he’s working hard and was a good compliment with Graziano [Pellè],” Koeman told youtube.com/southamptonfc
“They are different players because Shane is running more and he’s always busy, that’s a great quality of Shane.
“And then when he scores the winning goal it’s amazing for him and amazing for the team.
“You have always individual players like Shane who scored the winning goal, but it’s the total team performance.”
Koeman also believes the added competition for places in attack means the players will be giving as much as possible to keep their places.
“We have big competition in front and you like to start always with the best team, but sometimes it’s difficult,” Koeman added.
“But that’s the competition that the team needs to improve. We have really big competition in our squad.”