In the pursuit of Rangers that their season has developed into, Celtic are coming to rely on the diligence of their application. This was a performance without glamour or bold imagination, but enough purpose to be meaningful. They overcame Inverness through sheer perseverance.
The margin of victory was narrower than need be as, when 2-0 up and apparently coasting, Scott Brown gifted Inverness a way back into the game with 20 minutes to go, his casually misplaced pass allowing Marius Niculae to cut the arrears.
"It's always possible you could lose two points if you give a goal away like we did" said the Celtic manager, Gordon Strachan, who started his two-game touchline ban last night. "But I'm not going to stick bamboo shoots up his [Brown's] fingernails. It's something that you have to deal with."
Aiden McGeady remains the sparkle in the Celtic side and in the first half his quick feet carried him into range 25 yards out, but the Inverness goalkeeper Michael Fraser saved his shot at the second attempt.
The game appeared to be drifting towards the interval until Markus Paatelainen caught Andreas Hinkel with a shuddering challenge near the touchline. From the free-kick, Shunsuke Nakamura sculpted a cross into the centre that Scott McDonald turned past Fraser.
As though trying to protect his role as Celtic's most reliable and significant finisher, McDonald inadvertently blocked a goalbound Georgios Samaras shot after the break, but Samaras was rewarded with a precise McGeady cross that he headed past Fraser with a flourish.
After that Celtic's only peril was their own indifference. As Inverness refused to be overwhelmed, Brown inadvertedly set up Niculae and the Romanian striker struck a low effort beyond Artur Boruc. The home fans held their breath, but Celtic kept the game, and the points, in their grasp.
Celtic (4-4-2): Boruc; Hinkel, Caldwell, McManus, Naylor; Nakamura, S Brown, Donati, McGeady; McDonald (Killen, 82), Samaras. Substitutes not used: M Brown (gk), Hartley, Riordan, Sno, Robson, O'Dea.
Inverness CT (4-4-1-1): Fraser; Tokely, McGuire, Munro, Hastings; Imrie, Duncan, Black (McBain, 78), Paatelainen (Wyness, 78); Cowie; Niculae. Substitutes not used: Malkowski (gk), Kerr, Vigurs, Proctor, Gillespie.
Referee: W Collum.