And Koeman was impressed by Dutch international's display, feeling that he complemented Wanyama well during the contest.
"I think he played well," Koeman said to the Southern Daily Echo. “He was aggressive, I think he was a good couple on our midfield with Victor Wanyama and Jordy together.
“Ok, to know exactly if a player is really back you have to give the player that opportunity and sometimes it’s easier to start the game than to come on in the second half."
Clasie was Southampton's marquee signing during the summer transfer window, but his progress at St. Mary's has been halted so far.
The 24-year-old has missed much of the campaign so far with injury, but he is edging back to full fitness now, and looks set to play a big part.
Although Southampton have made an impressive start, Koeman has already found a place for Clasie in his starting line-up, and it seems that he is set to stay in the team for the foreseeable future.
Clasie will know that he will have to keep his high standards up if he is to keep his place, though, as Southampton have plenty of depth in the central-midfield area.