Upson's previous two caps have come in friendly internationals but Wednesdays 2-1 Euro qualifier victory means Blues have to pay the Premier League runners-up the fee.
Speaking about the game against Slovakia, in which England came from a goal behind, Upson said: "I feel a competitive game for my country is definitely the biggest game of my career.
"I enjoyed it very much and it would be nice to get more chances to play for England.
"I'm pleased I didn't look out of place. I enjoyed myself and felt sharp which I should have because my last competitive match was for Birmingham only four weeks ago."
