Viktor Gyokeres scored his first two Arsenal goals as the Gunners gave Leeds a harsh lesson in the step up to the Premier League with a 5-0 win at the Emirates.
Victory came at a cost for Mikel Arteta as Bukayo Saka and Martin Odegaard hobbled off injured just eight days before Arsenal's trip to Liverpool.
Arsenal edged ahead of north London rivals Tottenham at the top of the table on goal difference, as the only two sides so far with a 100 per cent record from their opening two games.
Saka fired in a blistering strike from a narrow angle to double the home side's lead after Jurrien Timber opened the scoring.
Gyokeres was signed from Sporting Lisbon as the solution to Arsenal's need for a killer No 9.
The Swede's ability to succeed in the Premier League has been questioned despite his prolific record of 97 goals in 102 games for Sporting.
Gyokeres made his mark with a fine individual run and finish before Timber bundled in his second from another Declan Rice corner.
Gyokeres rounded off the scoring from the penalty spot with virtually the last kick of the game.
A day of celebration for the home fans began before kick-off when new £60 million signing Eberechi Ezi was paraded after he turned down a move to Tottenham.
But the sight of captain Odegaard and talisman Saka leaving the field soured a routine win.
Arsenal had to rely on their threat from set-pieces to grind out a 1-0 win at Manchester United on the opening weekend of the season.
Despite a dominant start to the game, that was how the the Leeds defence was prized open.
Timber had scored just twice in 52 Arsenal appearances before Saturday.
The Dutch international doubled that tally as he firstly got his head to Rice's inviting delivery on 34 minutes.
Odegaard then made his departure after appearing to injure his shoulder falling heavily to the turf.
Saka soon had the Emirates crowd back on their feet when he drilled Timber's pass high past Lucas Perri with his supposedly weaker right foot.
Gyokeres had at one point been a target for Leeds during his days with Coventry in the Championship before making the move to Portugal.
Arsenal's new £66 million signing showed the Yorkshire side what they missed as he scampered onto Riccardo Calafiori's ball over the top and cut inside before firing in at the near post.
Saka missed nearly four months of last season with a hamstring injury.
Worryingly for Arteta, the England international was holding the back of his left leg when he was replaced on 53 minutes.
Arsenal added a fouth when Leeds failed to clear another Rice corner and Timber forced the ball over the line from close range.
Arteta could then afford the luxury of handing a Premier League debut to 15-year-old Max Dowman.
He became the second youngest ever player to play in the English top-flight after teammate Ethan Nwaneri.
Dowman's trickery won a penalty deep into stoppage time that Gyokeres gratefully dispatched.