Petr Cech won 13 trophies including four Premier League titles and the Champions League in 11 seasons with Chelsea before moving across London to Arsenal in 2015.
Arsenal must now turn the tie around in the second leg at the Emirates Stadium next Thursday if they are to progress any further in the Europa League.
Petr Cech's final game for the Czech Republic was the 2-0 defeat to Turkey in Euro 2016
Spain were frustrated throughout by the Czechs' stubborn defensive game, which finally fell apart when Gerard Pique got his head to Andres Iniesta's cross towards the back post where he beat goalkeeper Petr Cech in the 87th minute
Arsenal F.C. and second-place Leicester City have 44 points, with Manchester City a point behind in third.
Petr Cech's arrival from Chelsea has been acclaimed as a signing that could turn Arsenal into title contenders, but he was found wanting as Arsenal opened the Premier League season with a home defeat
Petr Cech moved across the English capital last month from Chelsea where he won four Premier League titles and the Champions League in 11 successful seasons.
Goalkeeper Petr Cech, who joined Arsenal last month from EPL champions Chelsea, has been part of Arsene Wenger's 27-player squad for the Barclays Asia Trophy.
Petr Cech has won four EPL titles, the Champions League, the Europa League, four FA Cup winner's medals and the League Cup on three separate occasions during his time at Chelsea. The Czech International move to Arsenal this season.
Petr Cech made 400 appearances during 11 years with Chelsea but said he is excited to join Arsenal.
Petr Cech denied any move to Arsneal being worked out currently, in a tweet from his official account.
Petr Cech has one year remaining on his contract at Chelsea but is searching for a new club after spending much of last season as second choice to Belgian goalkeper Thibaut Courtois, the first time he has not been No. 1 since moving to London in 2004.
Petr Cech has played as the second-string custodian to Thibaut Courtois this season after the latter returned from his loan at Atletico Madrid. Cech's representative said the keeper is keen to play in first-team football elsewhere.
Petr Cech, the Czech Republic international, is set to leave Chelsea this summer, with the club now prepared to part with the keeper only for 10 million pounds or above.
Petr Cech has played only four full Premier League games this season -- all in 2015 and all with a clean sheet -- against 25 appearances for Belgian international Thibaut Courtois, who is ten years younger.
Petr Cech, the club's number one since arriving at Stamford Bridge in 2004, sat on the bench during the 3-1 opening day victory at Burnley, with Thibaut Courtois named in the starting line-up.
Coach Holger Osieck defended his decision, saying he was "opening doors to talent" that caught his attention in a bid to test upcoming players at international level.
Schwarzer signed on a free transfer earlier this month after spells at Fulham and Middlesbrough and will provide valuable competition and motivation for number one goalkeeper Petr Cech.