Roberto Mancini knows Manchester City must improve their defensive prowess if they are to kick-start their Barclays Premier League title defence.

The champions had to settle for a third draw from five games in a 1-1 stalemate with Arsenal at the Etihad Stadium, after Laurent Koscielny equalised in the 82nd minute.

Mancini said: "In the last four games we've conceded three goals from set-pieces. This can't happen. If you want to win, clean sheets are important."

The result left City four points behind leaders Chelsea.

Meanwhile, Spurs gaffer Andre Villas-Boas was overcome with emotion after his first home win in charge of the club yesterday against QPR.

With his team 1-0 down at half-time, Spurs left the field to a chorus of boos but regrouped in time to claim all three points thanks to strikes from Jermain Defoe and Alejandro Faurlin.

Villas-Boas said: We wanted to repay the fans for the trust they have put in us so that's why everyone felt emotional."