Clive Mendonca hit a second-half hat-trick as promoted Charlton Athletic beat 10-man Southampton 5-0 and established themselves as the early leaders in the table.
John Robinson broke the deadlock in just the third minute and, although the Addicks were only leading 1-0 at the interval, they quickly raced clear of their visitors after the break.
Neil Redfearn doubled the advantage within a minute of the restart, and Saints goalkeeper Paul Jones was then sent off.
Mendonca scored a penalty eight minutes later and struck twice more in the closing stages to complete his treble.
The margin of Charlton's victory left them in top spot on goal difference, with four points, while Southampton found themselves at the foot of the table after defeats in their opening two matches.
Arsenal fought back from two goals down to beat Middlesbrough 5-3 and equal Nottingham Forest’s all-time league record of 42 unbeaten matches.
Thierry Henry gave Arsenal the lead, but Joseph-Desire Job levelled just before the interval and Middlesbrough led 3-1 in the 53rd minute after quickfire goals from Jimmy Floyd Hasselbaink and Franck Queudrue.
Arsenal's unbeaten run was under real threat. However, Dennis Bergkamp immediately pulled a goal back, and Robert Pires and Jose Antonio Reyes scored within seconds of each other to put the Gunners in front. Henry struck the eighth goal of the contest late on.
The result left Arsene Wenger's side top of the table, ahead of Chelsea on goal difference, while Middlesbrough dropped to 19th place.