Mackay expects Mauricio Pochettino's side to hand his side a tough test at Cardiff City Stadium, and pointedly referred to them as an example for the Welsh club to follow.
"Southampton is going to be a tough one," he said. "They are someone I look at and say there is a model which we have been trying to follow this year.
"They came up to the Premier League, they were the best team in the Championship when we played them and they invested well and are trying to do the right things with their football club and with the academy and it can be seen.
"They invested heavily last year and stayed in the league and this summer they invested heavily again and are making a real good way in the Premier League this year."