Gary Mackay-Steven and Stuart Armstrong both scored on their Celtic debut as they helped the reigning champions to a 3-0 win over Partick Thistle in their Socttish Premiership clash on Wednesday.

The pair, who joined Celtic from Dundee United on transfer deadline day, immediately started repaying their £2million fee with first-half strikes.

It took Mackay-Steven just 38 seconds to open his account for Celtic before Armstrong doubled his side's advantage in the 30th minute, the first time since 1987 that two Hoops players have netted on their debuts.

Celtic extended their lead in the 66th minute when Stefan Johansen drilled home a third as they recorded their seventh straight win and eighth consecutive clean sheet in all competitions.

The win moves Celtic three points clear of Aberdeen at the top of the Scottish Premiership and with a game in hand over their rivals.

Celtic boss Ronny Deila praised the consistency of his side. "I am very happy as it was a very difficult pitch to play on," the Celtic manager said.

"After the number of matches we have played now there is a danger there will be a dip but I think the performance was good and we won in a good way."

Alan Archibald rued his side's poor start. "It was a terrible start," the Partick Thistle manager said.

"I think when you play Celtic it's important you make them work for their goals and we gave them two goals certainly.

"Our season won't be defined by games against Celtic and we have important games coming up."

After two weeks off league duty due to their involvement in cup competitions, Celtic boss Ronny Deila handed both Armstrong and Mackay-Steven their debuts against Thistle and it didn't take long for them to show why they had been bought.

Mackay-Steven immediately played in John Guidetti whose blocked shot earned his side a corner.

The Thistle defence failed to deal with Johansen's corner allowing Mackay-Steven to take a touch before lashing it beyond Scott Fox after just 38 seconds.

Moments later Armstrong came close to adding another when he burst into the penalty box but his strike was pushed away by Fox before Frederic Frans poked the ball away as Guidetti attempted to pounce on the rebound.

He didn't have to wait long to join his fellow debutant on the score sheet as he added a second in the 30th minute.

The midfielder laid off Mackay-Steven's pass to Guidetti who, after recovering from taking a bad touch, returned the favour and Armstrong slammed home a shot from 15 yards.

Thistle eventually managed a shot on target just after the break when Declan McDaid drilled in a shot from 20 yards but 'keeper Craig Gordon easily dealt with his effort.

The home side then had a penalty appeal turned down when Stuart Bannigan's shot appeared to hit the elbow of Emilio Izaguirre before Lyle Taylor shot wide from a Ryan Stevenson cross.

However, Celtic were to add another in the 66th minute through Johansen.

The Norwegian midfielder took advantage of a mistake in the Thistle defence to latch on to a loose ball before drilling a superb strike beyond Fox.