Barcelona forward Lionel Messi kicks the ball during the Champions League againstManchester City in Barcelona on October 19, 2016.LLUIS GENE/AFP / Getty Images
After all the hype about Pep Guardiola returning to face his former club, Lionel Messi made sure it was no contest.
Messi scored a hat trick to deal a humbling defeat to his former mentor on Wednesday, leading Barcelona to an emphatic 4-0 victory over Manchester City in the Champions League.
Messi sped through City's defence and around former Barcelona goal keeper Claudio Bravo before giving the hosts the 17th-minute lead in a Group C match that both teams finished with 10 men.
It only got worse for Bravo, who was sent off in the second half for using his hands to block a shot outside the area after his poor pass gifted the ball to Luis Suarez.
Messi struck again in the 61st and 69th to take his total to 89 goals in Europe's top club competition. The Argentina forward is second only to Cristiano Ronaldo's 98.
Barcelona's substitute defender Jérémy Mathieu was sent off in the 73rd minute for a second yellow card.
Neymar rounded off the win from a pass by Messi, moments after the Brazil striker had missed a penalty that Messi had earned.
Guardiola lost for the second time upon returning to Camp Nou, where he established himself as one of the world's top managers by leading Barcelona to 14 titles from 2008-12. The former Barcelona midfielder coached Bayern Munich when the German side lost 3-0 at the Catalan side in the Champions League semi-finals two years ago, when Messi scored twice.
Barcelona leads Group C with a perfect nine points, City has four and Borussia Moenchengladbach three after its 2-0 win at last-place Celtic, which has one point.
In Group A action, Mesut Ozil fired a second-half hat trick as Arsenal took a big step toward the knockout stage with a 6-0 rout of Bulgarian champion Ludogorets.
The north London side, which is now unbeaten since the opening game of the season two months ago, tops the group with seven points.
Paris Saint-Germain also has seven points after its 3-0 home win over Basel, which is level on one point with Ludogorets.
In Group B action, Vincent Aboubakar scored twice as Besiktas beat Napoli 3-2 to deny the Italian club a chance of advancing from the group stage in record time.
In Group C action, in Glasgow, Borussia Moenchengladbach capitalized on two defensive errors by Kolo Touré to beat Celtic 2-0, earning the German team its first points.
In Group D action, Bayern Munich dispelled any doubts about its commitment by ending a three-match winless run with a comfortable 4-1 victory over PSV Eindhoven.