It was a night to forget for Manchester City when they travelled to the Camp Nou, despite making a promising start with high pressing, dangerous balls into the box and only conceding the one goal in the first half, it soon fell apart.
Within minutes of the second half beginning, Claudio Bravo's poor clearance left the Chilean in no-mans-land and his handling of the ball outside the area saw the former FC Barcelona man make an early exit.
Manchester City hammered in first tie at Camp Nou
This dismissal destabilised the entire team and City's momentum was compromised, ultimately leading to a 4-0 defeat, Lionel Messi netting a hat-trick in the process.
Luis Enrique's side won't be taking their foot off the gas tonight as Barcelona can secure qualification tonight with a victory over City, provided Borussia Mönchengladbach fail to beat Celtic.
Enrique has warned the Blues that should they make the same errors they did a fortnight ago, there would be no mercy from his side, who despite having the likes of Andres Iniesta, Jordi Alba and Gerard Pique absent will most likely be the bookmakers favourites tonight.
Enrique doubts City can improve pressing
''I don't think City can be any more aggressive in terms of pressure. They were pressing us up to the stand almost - to make the pitch as big as possible. If they leave spaces behind, we will take advantage," Enrique said.
City shouldn't be viewed as underdogs by any means given the quality they now possess and the superior game plan they have honed for weeks now meaning it'll be a closer tie than most might expect.
Only an exemplary performance will see City through given the irresistible front line of Lionel Messi, Neymar Jr, and Luis Suarez who will all be looking to add to their tallies, not to mention how delicately poised City remain in the table, a slip-up tonight could prove to be very costly.