Arsenal ruined Ange Postecoglou's first game in charge of Nottingham Forest as Martin Zubimendi's double capped a 3-0 win at the Emirates Stadium on Saturday.
Zubimendi bagged his first goals for the Gunners following his close-season move from Real Sociedad.
The Spain midfielder opened the scoring in the first half and netted again in the closing stages after Viktor Gyokeres doubled Arsenal's lead soon after the break.
Arsenal's third win in four games took them to the top of the table on goal difference ahead of Liverpool, who face Burnley on Sunday.
A 1-0 defeat against champions Liverpool in their last match before the international break had subdued the optimism at Arsenal after successive wins against Leeds and Manchester United to start the season.
But after Saturday's display, highlighted by Noni Madueke's virtuoso performance, Gunners boss Mikel Arteta will have high hopes of aiming for the title.
Postecoglou was back in a Premier League dugout 99 days after he was dismissed as Tottenham manager.
Postecoglou failed to win a north London derby during his Spurs tenure and Forest's last victory at Arsenal was 36 years ago. And Postecoglou's new side might have fallen behind after just seven minutes when Mikel Merino saw his point-blank effort diverted from danger by Matz Sels.
Arsenal captain Odegaard lasted only 17 minutes after he fell awkwardly on his right shoulder following a robust, but fair, challenge from Morgan Gibbs-White.
Odegaard was withdrawn in the first half of Arsenal's last game at the Emirates with a similar injury, and he was visibly upset when he made his way to the touchline to be replaced by Ethan Nwaneri.
Eberechi Eze was handed his first start but it was Madueke on the opposite wing who caught the eye throughout. On the half-hour mark, he danced past Dan Ndoye to the byline only to see his pullback cleared off Jurrien Timber's toes by Murillo.
But from the resulting corner, Arsenal had their breakthrough. Chris Wood's header from Madueke's inswinger fell to Zubimendi on the centre of the arc, and the Spaniard's thumping volley swerved away from Sels.
The hosts doubled their advantage inside the first minute of the second half. Riccardo Calafiori's ball over the top found Eze, just onside, and his pass across the six-yard box was converted by Gyokeres.
There was a warning sign for Arsenal when Ndoye's cross thudded into Wood's chest with the ball looping over David Raya, who managed to get his fingertips to the ball and turn it on to the crossbar.
Gyokeres came close to doubling his tally when his effort from Madueke's no-look pass rattled the frame of Sels' goal.
Madueke's move from Chelsea saw a social media backlash from some Arsenal fans but he was Arteta's star performer and received a standing ovation from the Emirates Stadium crowd when he was replaced with 12 minutes to go.
Moments later, the home supporters were celebrating a third when Trossard's first kick from coming off the bench was met by the head of Zubimendi.
After the match, Forest manager Postecoglou said it was a tough start to the job.
"Obviously a disappointing outcome for us. They're a good side and at home, they're a tough proposition," he told TNT Sports.
"Can't fault the lads' effort but we struggled to get a grip of the game and the second goal after half-time just allowed them to get away from us. Disappointing but can't fault the effort."
