A score draw will be enough to see Bahrain past Saudi Arabia and into a World Cup finals qualifying play-off with New Zealand but still the Arabic island country is feeling the pressure ahead of Wednesday's clash.
Milan Macala's side were held to a 0-0 draw in Saturday's home leg in Manama and, despite keeping a clean sheet, their Czech coach admits he is not sure whether to be confident or not.
"The first game was good and our players were impressive, but to be honest, I don't know whether the result is good for us or not," Macala told reporters.
"We wasted a lot of chances and were not fortunate," added the Czech tactician, who coached Saudi Arabia a decade ago.
Bahrain have never reached a World Cup finals while Saudi Arabia have competed in the last four.
Bahrain will face an intimidating atmosphere at the King Fahd International Stadium, where 65,000 fans watched June's final Group B clash against North Korea.
On that occasion the visitors escaped with an automatic spot at South Africa after a goalless draw and Macala hopes for a similar upset on Wednesday.
"The first-leg result puts a lot of pressure on our players in the next game, but this is natural as we'll be playing away and Saudi Arabia are at home and in front of their fans," said Macala, whose time in the Middle East has also included stints with Kuwait, the UAE and Oman.
"The first game was really hard for us, although we controlled the game, while Saudi Arabia defended deep and tried to hit us on counter-attacks. Probably the pressure on the Saudi players affected them."
Saudi coach Jose Peseiro was giving nothing away.
"It was a positive game in Bahrain from both teams who tried to score, but couldn't," said the Portuguese.
"Of course, it could have been better had we won the game, but we will give our best on Wednesday to win at home."
The winners of the Asian Football Confederation play-off will compete against Oceania Football Confederation champions New Zealand in a home-and-away play-off on Oct. 10 and Nov. 14 for a place in next year's World Cup in South Africa.