Leeds Rhinos say the player who was awaiting a coronavirus test result before Friday's Super League win over Huddersfield has tested negative.
Seven Leeds players were stood down from the fixture at St Helens' Totally Wicked Stadium as a precaution, as part of track and trace protocols.
Leeds said in a statement that all players will return to training on Monday as normal.
The Rhinos won 13-12 with a late drop-goal from Luke Gale.
Leeds head coach Richard Agar said: "At 6.30pm we were not quite sure what our team was going to be.
"The six guys (who were in close contact with the player earlier in the week) drove over in the hope the email with the results was going to land before 6.30pm and we had to put a contingency team together.
"The email didn't come before we had to put our team sheet in.
"It's just where we're at. Everybody has been impacted and we're not going to complain. We're going to get a team out as much as we can and adapt to any situation we need to. It's important we keep the game going."