Dusan Tadic said Southampton have the confidence they can finish in the top four after their historic success against Manchester United gave them back-to-back victories against two of the Premier League's biggest clubs.
The Serbian winger became the first Saints player since Colin Clarke in 1988 to score a winner at Old Trafford in Sunday's 1-0 triumph over Louis van Gaal's team.
In their previous league game, Ronald Koeman's side defeated Arsenal, another of their rivals for a Champions League spot, and Tadic said: "It gives us huge belief.
"We just need to believe in our skills and to see what is good and what is not good, and to keep going. We beat two great opponents, Arsenal and Manchester United -- direct opponents for what we want.
"Yes, you pass Arsenal, you pass Man United beating them, and it's really important."
Southampton, who finished eighth last season and then sold five key players, have not finished in the top four since they were runners-up in 1984.
Tadic added: "The top four is possible but we have to go game by game. We have beaten good opponents and we have to keep doing this."
The former FC Twente player's introduction was delayed when he could not find his shirt, and manager Koeman then criticised him for taking it off after he scored, bringing a booking.
"There was no shirt -- I'd left it in the dressing room." Tadic said. "When you score you don't think about what you will do. Normally I don't do that [take shirt off], but this time I did."