Celtic's quality rises to the top in a one-sided tie
Celtic booked their place in the last four of the William Hill Scottish Cup with a comfortable 4-0 quarter-final replay victory over Dundee United at Parkhead as both sides ended with 10 men.
Ronny Deila's side beat United 2-0 in the Scottish League Cup final at Hampden on Sunday and any thoughts of Tayside revenge all but ended in the 17th minute when Hoops defender Jason Denayer headed in a free-kick from Anthony Stokes.
In the third meeting between the clubs in 11 days - the fourth comes in the Scottish Premiership at Celtic Park on Saturday - Leigh Griffiths, Kris Commons and Virgil van Dijk added further goals.
In the last two clashes, four players had been sent off - three from United - so there was no real surprise when, in the closing stages at 3-0, numbers were depleted.
Stokes was shown a straight red card for lashing out at Paul Paton before United defender Ryan McGowan was sent off for a bad tackle on Hoops' late substitute Liam Henderson.
Celtic set up a semi-final meeting with Inverness at Hampden Park on the weekend of April 18-19 and on this form, the league leaders' quest for the domestic treble looks much more likely than not although the next game against United at the weekend may not be for the squeamish.
Goalscorer Griffiths said: "We started the first half well and played at a high tempo. I don't think Dundee United could live with that. I knew I was coming off. It seems to be a habit that I score then I come off. Kris did that too.
"Scott Brown gave me a great pass. He came over afterwards and said, 'I bet you didn't expect that!' He's a big character in the dressing room but when it comes to match days he's focused.
"It was a great pass and I just had to compose myself in front of goal."
Jackie McNamara has to pick his men up for a return trip to Glasgow on Saturday for the final game of four consecutive matches against Deila's side.