Tony Watt scored a double on his first Celtic start as Neil Lennon's injury-hit side swept to a 4-2 victory at Inverness.
The 18-year-old produced a brilliant piece of skill, a good turn of pace and a composed finish in the 24th minute to add to Victor Wanyama's early headed opener.
Charlie Mulgrew fired Celtic three ahead just after the break and Watt was on hand to make it 4-0 in the 64th minute. However, Celtic switched off the final ten minutes and Ross Draper scored two consolations.
Celtic could have been further out of sight by then with Watt showing more of the promise that he first announced in the Celtic first team when he scored a double against Motherwell within six minutes of coming on for his debut.
Dundee United's impressive start to the season came to an abrupt end with a 3-1 defeat to Kilmarnock.
After a goalless first 45 minutes, a mix-up at the back for United allowed Rory McKenzie to steal in and open the scoring on his debut. Two minutes later, they doubled their lead courtesy of a Borja Perez spot-kick after Mauel Pascali was brought down by Gary Mackay-Steven. Jude Winchester fired in a third before Jon Daly replied for United 11 minutes from time.
Hibernian made it back-to-back wins in the league with a 2-0 success against St Johnstone at Easter Road.
The home side were second-best throughout the first half but took a 1-0 advantage into the break thanks to a 45th-minute goal by Paul Hanlon. Eoin Doyle added the second six minutes after the restart.
The defeat leaves St Johnstone joint bottom of the division with only one point taken from their opening four games, while Hibs move up into second.
A Richard Brittain penalty was enough to give Ross County their first league win of the season as they beat Dundee 1-0.
The Staggies, now unbeaten in 38 league games, netted the winner with less than 20 minutes remaining after Mark Corcoran had been impeded by Neil McGregor.
The defeat leaves Dundee at the foot of the table with only one point from their opening four matches.