Inverness took the lead through Josh Meekings's first ever goal on 16 minutes, but Adam Rooney and Shaleum Logan turned the game on its head going into the break for Aberdeen. Marley Watkins equalised for the visitor but it was Jonny Hayes who won the match in the 59th minute for the hosts.
Motherwell were well beaten by Hamilton Academical at home after Tony Andreu's and Ali Crawford's first-half goals put the away side 2-0 up at the break. Mickael Antoine-Curier then added another on 63 minutes before Crawford doubled his tally in the final minute to make it 4-0.
Michael Gardyne opened the scoring for Ross County in the 27th-minute, but David Clarkson's equaliser with 20 minutes remaining levelled the scores for Dundee. Darren Maatsen scored a dramatic late goal for the hosts to win their first match of the season in the 90th minute.
Results in full: Aberdeen 3-2 Inverness Caledonian Thistle, Dundee United 2-0 St Johnstone, Kilmarnock 3-0 Partick Thistle, Motherwell 0-4 Hamilton, Ross County 2-1 Dundee.