Are Celtic club in regression amid run of six defeats in 10?

Europe aside, Celtic's season had been rattling along relatively well.

They had bounced back from League Cup and league losses to Rangers with a solid win at Motherwell, a resounding 7-1 victory at home to last season's runners-up Hearts, and a hard-fought 2-1 win from behind at Hibernian.

Wednesday's 2-2 draw with Dundee United turned out to be a missed opportunity to extend their lead at the top and they now face the prospect of Rangers and, indeed, Hearts getting closer should they win their games in hand.

Besiktas in the Europa League are next up, a home game Celtic really need to win to stand any chance of progress in that competition after starting with three defeats.