Cech, who is set to retire at the end of the season, said that their away goal could prove crucial when the teams meet at the Emirates Stadium in next week's return leg.
"We can still overcome a two-goal deficit because in the end the goal we scored might play a big part, but we made it a bit harder for ourselves," the 36-year-old told the club's website.
Arsenal can also take inspiration from Ajax and Manchester United, who produced stunning comebacks to reach the Champions League quarter-finals this week by knocking out holders Real Madrid and big-spending Paris St Germain respectively.
"We created chances ... so we have to be positive," Cech added. "We've done it in the past where we've been 2-0 down and have overcome the deficit."
Arsenal host United in the Premier League on Sunday, hoping to reclaim fourth place in a bid to secure Champions League soccer next season.
Unai Emery's fifth-placed side have 57 points from 29 matches, one point fewer than United.
(Reporting by Shrivathsa Sridhar in Bengaluru, editing by Nick Mulvenney)
