Messi treble gives Guardiola nightmares on Barca return

* Lionel Messi grabbed hat-trick for Barca

* Former Barca keeper Claudio Bravo was sent off

* Neymar penalty saved before he notched fourth goal

* Teams to meet again at the Etihad Stadium on Nov. 1

Lionel Messi scored his second hat-trick in as many Champions League games to give Barcelona a 4-0 win over Manchester City as Pep Guardiola and Claudio Bravo endured harrowing returns to the Nou Camp on Wednesday.

A slip by Fernandinho allowed Messi to round former team mate Bravo and open the scoring in the 17th minute and the keeper completed a miserable night by getting sent off in the second half for handling outside the area after losing the ball.

The magical Messi hammered in his second from the edge of the area after turning two City defenders and pounced on a Luis Suarez lay-off to complete his treble in the 69th minute.

Barca substitute Jeremy Mathieu was then dismissed for two bookable offences. Neymar had a late penalty saved by substitute Willy Caballero but the Brazilian made amends by scoring the fourth goal in the 89th minute.