'Ferrari must improve'

Ferrari's Fernando Alonso won back-to-back titles with McLaren in 2005 and 2006.Fernando Alonso warns Ferrari must improve if he is to win F1 titleThe Spaniard has a 29-point advantage at the top of the drivers' standingsAlonso finished Singapore GP in third place, after starting fifth on the gridThe next Grand Prix is in Japan on October 7

(CNN) -- Formula One world championship leader Fernando Alonso has warned his Ferrari team they must improve if he is to win the marque's first drivers' crown since 2007.

Alonso finished third at the Singapore Grand Prix, extending his lead at the top of the 2012 standings to 29 points with just six races of the season to go.

But the two-time world champion knows Ferrari cannot continue to rely on their rivals slipping up, after McLaren's Lewis Hamilton was forced to retire from a winning position on Sunday.

"In the end it went well, but we definitely can't go on like this," the Spaniard, who saw his nearest rival Sebastian Vettel of Red Bull take the checkered flag, told Ferrari's official website.