Southampton stayed five points clear at the top of the Championship after winning a thrilling game at Coventry.
Richard Chaplow opened the scoring when he swept home from 12 yards before Adam Lallana added a second from six yards.
Goals from Lukas Jutkiewicz and Clive Platt levelled things for the home side, but Saints were not to be denied.
Guly do Prado headed home to restore the lead before Steve de Ridder added a fourth to make it 11 wins out of 16 league games for the visitors.
The win keeps Nigel Adkins' side five points clear of West Ham at the top of the table and ensured their best start to a season for 90 years.
Chaplow and Morgan Schneiderlin both went close before the deadlock was broken by Chaplow and Lallana had an excellent chance just before he did find the target on 39 minutes.
The visitors dominated proceedings at the Ricoh Arena but Andy Thorn's half-time team talk clearly did the trick as the home side got back on level terms.
Jutkiewicz fired past Kelvin Davis before Platt took advantage of a deflected shot and rolled home.
Parity lasted just seven minutes before Southampton were back in front through Do Prado.
De Ridder made sure of the points with five minutes to go, converting from the middle of the penalty area.