McDonald gave Celtic the lead on the stroke of half-time
Celtic kept the pressure on league leaders Rangers with a hard-fought win over Inverness CT at Celtic Park.
Inverness keeper Michael Fraser kept the hosts at bay before Scott McDonald swept home Shunsuke Nakamura's free-kick on the stroke of half-time.
Georgios Samaras was denied twice by Fraser before despatching a bullet header past the keeper in 60 minutes.
Marius Niculae pulled one back for Inverness when he pounced on Scott Brown's misplaced pass to score.
Celtic made two changes to the team that beat St Mirren at Love Street on Sunday.
Midfielders Barry Robson and Paul Hartley dropped to the bench and were replaced by Shunsuke Nakamura and Massimo Donati.
Inverness player-manager Craig Brewster made one change to his side which lost to Hibs, striker Markus Paatelainen coming in for Graham Bayne who dropped out of the squad.
Georgios Samaras doubled Celtic's advantage with a bullet header
Celtic pressed for an early opener and Samaras raced past Grant Munro into the box but his 15-yard drive was blocked by Fraser.
The Greece international was thwarted again in the 20th minute when Fraser saved his drive low to his right.
McDonald eased nerves among the home support when he flicked home Nakamura's free-kick just before half-time for his 25th goal of the season.
Celtic's second goal came on the hour mark when Samaras headed Aiden McGeady's cross powerfully past Fraser from eight yards.
Gordon Strachan's side then endured a nervy end to the game after Niculae pounced on Brown's poor pass to fire pass Boruc.
But Celtic held on to ensure Rangers' lead at the top of the SPL remains four points.
Celtic: Boruc, Hinkel, Caldwell, McManus, Naylor, Nakamura, Donati, Scott Brown, McGeady, McDonald (Killen 83), Samaras. Subs Not Used: Mark Brown, Hartley, Riordan, Sno, Robson, O'Dea.
Goals: McDonald 45, Samaras 61.
Inverness CT: Fraser, Tokely, Munro, Duncan, Black (McBain 78), McGuire, Cowie, Hastings, Imrie, Niculae, Paatelainen (Wyness 78). Subs Not Used: Malkowski, Kerr, Vigurs, Proctor, Gillespie.
Booked: Imrie, Hastings.
Goals: Niculae 70.
Ref: W Collum