Scotland assistant Peter Houston says a victory over Czech Republic on Saturday is a must if hopes of Euro 2012 qualification are to be retained.
The Scots go into Saturday's Group I game five points behind the second-top visitors but with a game in hand.
"I am looking at the Czech Republic game and thinking we have to win," admitted Houston.
But he warned that the Lithuania game three days later could prove just as difficult.
The Czechs will arrive in Scotland for the match at Hampden on the back of a 3-0 defeat by Norway in a friendly last month.
"They have had a poor result against Norway, but please don't underestimate them because of that," said Houston.
"In many ways, it could make them more determined to do well and it might be the kick up the backside they were maybe needing to get their minds focused again.
"We will be very wary of the Czechs as we know they have quality players, but we have some quality players as well."
Indeed, Houston believes that the Scots have improved since Craig Levein took over as coach and go into the game full of confidence following last month's 2-1 win over Denmark in a friendly.
"The fact that everybody has turned up is unique in many ways," he said.
"I can't remember when any Scotland squad has had no call-offs.
"We've been a wee bit lucky and thankfully, when we need our strongest squad available, we are here sitting today with everybody fit and healthy.
"I think it tells you when there's no call-offs. It tells you again that everybody wants to be here and looking forward to what should be a great game on Saturday."
Houston hoped that a good result for the national team could lift the gloom following the exit of all four club sides from European football but said that everyone was in good heart.
"They're a fit bunch, they are good players and they pass the ball well," he said.
"When we look back at the games in video analysis, we are getting there as a team that can retain possession well and shift the ball about.
"And we have players playing in the highest league, the English Premier League, who are playing regular and players in the top league in Scotland.
"I think, over the period of time Craig has been manager, we have built gradually and we're getting there."
In contrast, the Czechs have injury problems, with the most high-profile absentee being Chelsea goalkeeper Petr Cech.
"I think the Czech Republic are a quality nation," stressed Houston. "They have had a blow with the fact that their goalkeeper is missing.
"He plays an awful lot of games for them and the second and third goalkeepers don't play a lot. He is a big influence on the team.
"But they have some good quality back-up as well, so we expect a very tough game.
"I think the last time we played them in a friendly game, they kept the ball well and moved the ball quickly."