Two-goal Jhon Viafara set his sights on winning promotion with Saints next year after doubling his tally for the club.
Viafara had only scored two goals in 39 appearances before last night.
He ccould not have picked a better time to net his first Saints brace.
The Colombian responded to the opener by capitalising on a Stephen Bywater mistake and thumping in the equaliser within a minute of Derby's first goal.
And after Leon Best's good work, he crashed his and Saints' second inside Bywater's near post.
Viafara said: "They were fantastic goals for me to score at important times, especially the first as they had just gone in front. It got us back into the game quickly.
"If it had gone on much longer without us equalising it would have been much harder to get back into it.
"I put a lot of power into the second, there was no way he was going to stop that, but I feel desperately sad because the whole team played so well and it's always so much worse to lose on penalties.
"To score three goals away and still not go through is hard to take.
"It's a shame away goals didn't count double but they are the rules, and we knew that".
Viafara is already looking forward to making up for the disappointment next season.
He added: "This team needs to be in the top flight and I want to play there with Southampton.
"Now we go away and relax, think about what has happened this season and be ready for the next one. I want to win with this team".
Derby v Saints: Seven pages of the best reports, reaction and pictures from Pride Park in today's Daily Echo.
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