Saints supporters were delighted with the dynamic duo after they helped their side to an historic 8-0 victory over the Black Cats.
"I'm still in a little bit in shock," Koeman admitted to reporters after the historic win. "Not about the second half, I think we played very good and scored some great goals, but about the first 20 minutes because I wasn't very happy about our performance at the beginning.
"Sometimes football is strange. I am disappointed for Gus Poyet because they played well at the beginning and had some good chances.
"It was an unlucky own goal and maybe at 2-0 they should have had a penalty but after that we deserved to win and I am very proud of the team to fight until the last second to score the goals."
Opta stats show just how key Pelle and Tadic were to Southampton's victory, with the former scoring twice and Tadic registering no less than FOUR asissts.
Saints fans were thus left basically worshipping them on Twitter, while many Liverpool supporters even asked why Brendan Rodgers couldn't have simply picked out the pair instead of signing Adam Lallana and Rickie Lambert from St Mary's for a higher cost!
Here are the best fan reactions on Twitter...
Dusan Tadic and Graziano Pelle are so so good. Best bit of buisness this summer in the league. COYR #saintsfc— Saint Rhys (@RhysTheSaint) October 18, 2014
What an unbelievable performance - I just am in shock - Tadic, Pelle, Cork, Clyne simply sublime #saintsfc— Paul Arnold (@ArnieTTR) October 18, 2014
Who needs lallana and co when you have pelle and tadic #saintsfc— Javesy (@Javalarr) October 18, 2014
Tadic: 7 Assists & 1 Goal Pelle: 6 Goals & 1 Assist Bertrand: 4 Clean Sheets, 1 Goal and 1 Assist. Shaw, Lambert and Lallana's Replacements.— Southampton Saints (@SaintsRelated) October 18, 2014