New striker Georgios Samaras made an instant impact by grabbing a debut goal as Celtic thrashed Kilmarnock in the Scottish Cup fifth round at Rugby Park.
McDonald celebrates after scoring his second, and Celtic's fourth goal
Scott McDonald began the scoring after 22 minutes when he swept home Paul Caddis' whipped cross from close range.
Gary Caldwell headed a second on 52 minutes and Jan Vennegoor of Hesselink struck on the hour mark before Jamie Hamill's goal handed Killie a lifeline.
But McDonald scored again and then Samaras completed the rout late on.
Kilmarnock had an opportunity to put Celtic under pressure early on when Willie Gibson's corner broke to Garry Hay but his shot lacked power and was easily cleared.
At the other end, Aiden McGeady tried his luck with a 25-yard drive which fell well wide of the target.
Scott Brown then embarked on a surging run down the right flank before delivering to the feet of Vennegoor of Hesselink.
The Dutch striker stumbled over the ball and recovered to have another go but the effort was blocked by Combe.
Celtic cranked up the pressure and McDonald forced a superb point-blank save from Alan Combe.
But the Killie goalkeeper could not prevent the striker from opening the scoring seconds later.
Caddis collected a neat reverse pass from Shunsuke Nakamura on the right wing and delivered a precise cross to McDonald who swept home from close range with 22 minutes on the clock.
Vennegoor of Hesselink then saw his header crash off the inside of the post before McDonald was twice thwarted in his attempts to net from the rebound.
Martyn Corrigan and Gibson both came close for the home side but Celtic managed to protect their lead heading into the interval.
Celtic claimed their second goal just seven minutes after the restart.
Nakamura's corner was flicked on by Massimo Donati and Caldwell connected powerfully to leave the net bulging with a header from a few yards out.
Vennegoor of Hesselink then helped himself to a goal six minutes later.
McGeady's pass split the Killie defence and found the Dutchman unmarked and with plenty of time to pick his spot.
Kilmarnock gave themselves hope of a comeback when Hamill nodded home from Danny Invincibile's cross after 65 minutes.
But the joy was short-lived when McDonald pounced on Vennegoor of Hesselink's lay-off to bury a firm shot from 12 yards a minute later.
Substitute David Fernandez and Craig Bryson went close for Killie before Celtic's Nakamura slid a right-foot shot just wide after a surging run.
New recruit Samaras replaced McDonald with 20 minutes remaining and instantly endeared himself to the travelling supporters by marking his debut with a goal.
The Greek striker used his strength to hold off Simon Ford on the right flank before darting infield and tucking a neat left-footed shot beyond Combe to round off a perfect day for the cup holders.
Kilmarnock: Combe, Corrigan, Hay, Ford, Frazer Wright, Fowler, Bryson, Hamill, Gibson (Fernandez 45), Wales, Invincibile (Di Giacomo 75). Subs Not Used: Harpur, Johnston, O'Leary.
Booked: Hamill, Fowler.
Goals: Hamill 66.
Celtic: Boruc, Caddis, Naylor, McManus (O'Dea 76), Caldwell, Donati, McGeady, Scott Brown (Sno 81), Nakamura, Vennegoor of Hesselink, McDonald (Samaras 67). Subs Not Used: Mark Brown, Hartley.
Booked: McDonald, Vennegoor of Hesselink, McGeady, Scott Brown.
Goals: McDonald 22, Caldwell 52, Vennegoor of Hesselink 58, McDonald 67, Samaras 85.
Ref: I Brines (Scotland).