Geoff Parling admits the British and Irish Lions 14-12 defeat to the Brumbies at Canberra Stadium "hurts like hell".
Warren Gatland's side were dealt a major setback as they suffered their first tour defeat Down Under.
It was the first time they had lost to any provincial team since South African side Northern Transvaal beat them 16 years ago.
And after scoring 261 points and 33 tries in winning five successive games, it was a huge blow - just four days before the first Test against Australia.
"We spoke straight after the game, and we've got to pick ourselves up straightaway," said Leicester lock Parling.
"We can't mope around. This hurts, it hurts like hell, but you can't start feeling sorry for yourself. There are some massive games around the corner.
"We can't afford to have our heads down. That is not just with the game at the weekend in mind, but I am thinking as well about the environment and going back to the hotel.
"If people mope around then that might spread. We just can't afford to be like that. We have a massive game at the weekend and we need to pick ourselves up and get back on the horse.
"You can't feel sorry for yourself. You put a brave face on it and you move on. We need to face this and get on with it."
The Lions will be aiming for a first series triumph since their victory in South Africa in 1997.