Rangers claimed their second Old Firm derby win in seven days as a single goal from Ryan Naderi claimed the three points at Celtic.
Derek McInnes' side were much the better team on Sunday and would have won by more if it weren't for VAR ruling out Olwethu Makhanya's volley for a handball.
- Celtic, Rangers away fans not allowed at Old Firm derbies this season
It came after Rangers' 3-0 win over Celtic last weekend, when two summer signings got the goals, as Dan Neil -- who arrived from Sunderland in July -- bagged a brace either side of Kevin Kelsy's first goal for Rangers since arriving from the Portland Timbers.
There was more bad news for Celtic in midweek as they lost 3-1 at home to Ferencvaros in the Europa League.
Liam Scales' 20th-minute own goal gave the Hungarian side the lead, before Mika Baur equalised for the hosts. But goals from Kristoffer Zachariassen and Daniel Arzani either side of halftime ensured Celtic conceded three and lost for the second time in five days.
It has been a different story for O'Neill's side in the league however, where they came into Sunday with six wins from six having beaten Dundee, Kilmarnock, Falkirk, Aberdeen, St. Mirren and St. Johnstone.
Rangers started Sunday five points back having drawn and lost their opening two games against Dundee United and Hibernian, respectively.
But Derek McInnes' side have gone on a five-match winning streak in the league since then, beating Aberdeen, Motherwell and St. Mirren 1-0, plus a 2-1 win at Falkirk and Sunday's victory over Celtic.
The run has helped to somewhat ease the pain of missing out on Europe altogether as they lost their Europa Conference League playoff 4-3 on penalties to Jablonec.
