Celtic booked their place in the Scottish Cup fifth round with a 2-1 win win over Alloa which ended with a hint of nerves for the Parkhead side.
First-half goals from Greek striker Giorgos Giakoumakis and winger Liel Abada had the Hoops comfortably ahead by the interval against the cinch League One side at the Indodrill Stadium.
That former Rangers captain Barry Ferguson was the hosts' manager added spice to a tie which became interesting when Alloa striker Conor Sammon's header reduced the deficit with 12 minutes left.
Celtic denied their hosts any clear-cut opportunities to draw level but their victory came at some cost for Ange Postecoglou as skipper Callum McGregor, Abada and Yosuke Ideguchi had to go off with various injuries.
Postecoglou made five changes from the team that beat Hibernian 2-0 on Monday with Japan's Ideguchi making his first start and Liam Scales, Anthony Ralston, Stephen Welsh and Giakoumakis back in the side.
Alloa, eighth in League One, started with some purpose and had a chance in the third minute when Sammon spotted Hoops goalkeeper Joe Hart off his line but his attempted chip from long range sailed high over the bar.
There was little between the side in the early stages, but the complexion of the match changed in the 14th minute when Scales sent in a cross from the left and Giakoumakis volleyed in with some assurance at the front post for his second goal in green and white.
Moments later, with the home side reeling, the striker forced his way into the Alloa penalty area but scooped his finish just wide of the target.
Celtic took control on the artificial surface and on the half-hour mark Alloa keeper David Hutton made a good reflex save from Daizen Maeda's close-range strike.
However, Hart had to come to Celtic's rescue in the 37th minute when, in a rare Alloa attack, Sammon got a shot away, with the ball coming off the keeper's leg and away to safety.
There was some Celtic concern two minutes from the break when skipper McGregor had to go off with a head knock following a clash with Adam King.
With seconds of the half remaining, Celtic doubled their lead when Abada cut in from the right and from 25 yards fired an unstoppable shot past Hutton.
The cinch Premiership side kept a grip on the game after the break, even when Jota replaced the injured Abada in the 52nd minute.
Hutton did well to push Maeda's diving header from Jota's cross past the post for a corner which came to nothing.
Ideguchi was crunched in a tackle by Mouhamed Niang which earned the Alloa player a booking from referee Don Robertson and the Hoops midfielder had to go off with Nir Bitton coming on as Postecoglou surveyed another casualty.
The Parkhead men were far from relentless but nevertheless Hutton saved a weak header from Giakoumakis before Maeda missed the target with only the Alloa keeper to beat.
However, the game took an unlikely turn when Sammon headed in a cross from Jon Robertson and the home side got a second wind.
Celtic were forced to up the tempo again and twice brilliant blocks from Alloa defender Andy Graham stopped Giakoumakis' shots getting through on goal and the home side never really came close to taking the tie into extra time.
