Charlie Mulgrew says Celtic's Scotland squad members can put international disappointment behind them to prepare for St Mirren then Barcelona.
The defender was involved along with Scott Brown, James Forrest and Kris Commons as the Scots suffered back-to-back World Cup qualifying defeats.
"It was a couple of bad results for us and it was disappointing," said Mulgrew, who was an unused substitute.
"But you need to quickly switch your mind towards club duties."
Celtic manager Neil Lennon suggested that the players had returned deflated from Scotland duty and had warned of a negative reaction at St Mirren Park.
Indeed, Brown and Forrest were back early after withdrawing through injury, while Commons picked up a knock against Belgium, making all three doubts for the Scottish Premier League encounter.
Some of Celtic's foreign players have only just arrived back in Scotland and he recalled that his side were defeated 2-1 away to St Johnstone immediately following the last international break.
"It is about being positive and not dwelling on it too much," said Mulgrew.
"We have done that now and we're looking forward to St Mirren.
"A lot of people arrived back late and just arrived back today, so the manager's drilled it home that we need to be 100 per cent concentrated and focused and we'll be doing that."
In the absence of traditional rivals Rangers, Celtic are strong favourites to retain their title and are already two points clear of Hibernian at the top with a game in hand.
However, Mulgrew insisted there would be no complacency in Paisley and discounted the possibility that thoughts would already be turning to Tuesday's visit to the Nou Camp.
"You don't just expect to win games," he said. "You need to earn it and hopefully we'll do that on Saturday.
"You have to look forward to St Mirren and deal with domestic stuff first.
"You can think of Barcelona come Sunday.
"It is the biggest club in the world and it's a huge game, so it's massive for the club and everybody involved will enjoy every minute of it.
"But, first of all, we need to concentrate on Saturday and get the result at St Mirren."
Mulgrew thought Celtic's victory in their last European venture, away to Spartak Moscow, had helped lift Scottish spirits.
"I think Celtic, as a club, are flying the flag well for Scottish football and I think it can only be good for our game," he added.