Paul Ince hailed Alen Boksic as the complete striker and then warned: "He can get even better!"
The Croatian ace scored a clinical double to give Middlesbrough their first win at The Dell since 1989 with Gianluca Festa adding the other in a 3-1 success.
His display drew glowing praise from Ince who has played with and against some of the world's best frontmen during his career with Manchester United and Inter Milan.
He said: "Alen is a quality player. He is as complete a striker as any I have played with.
"Most strikers have great finishing ability but he is strong too. He has got everything and he is big so you can put it in the air for him.
"He is quick as anything and if you want to progress in the Premiership you need a player like that - and he will get stronger.
"We have not seen the best of him yet. When he is 100 per cent fit he will get even better.
"He has settled in very well and mixes with the lads which is not always the case with foreign players."
Ince, who needed stitches in a knee wound, vowed to be fit for England's Wembley farewell against Germany on Saturday.
He added: "A game like this will be a fitting end for Wembley and I would love to be involved. We have not beaten the Germans there since 1966 and it would be a great send-off for the stadium."
Goalkeeper Gary Walsh limped off with a thigh injury to be replaced by Mark Crossley nine minutes from time and manager Bryan Robson now faces an anxious wait to see how it settles.
He was delighted to see his side's fine away form continue and admitted he was sweating when Southampton pulled a goal back 11 minutes from time.
He said: "Saints came from three down to draw at home to Liverpool recently so we knew they are a difficult side to play against when they are chasing the game.
"They have some big lads and are dangerous from crosses but our away form has been good for some time now and we have nothing to fear going anywhere."
Southampton boss Glenn Hoddle, who signed an 18-month extension to his contract before the game, also pinpointed Boksic as the difference between the sides as his side's four-game winning run came to an abrupt halt.
Hoddle said: "They had four attempts at goal and scored three of them. The difference was Boksic who was a class act and a cut above anything else on the pitch.
"Every time he had the ball in the final third he looked like scoring. His style seems to suit playing away from home.
"We had enough possession and efforts on goal to win the game but we went a bit negative after the first goal.
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