CALLUM McGREGOR says it is vital that Celtic tighten up at the back ahead of their Europa League third-round qualifier against Latvian side Riga following their 3-2 win over Livingston.

The Premiership champions had to come from behind to beat St Mirren in the Scottish Premiership in midweek and again on Saturday they suffered an early scare as Jason Holt converted from the penalty spot to give the visitors an unlikely lead.

Midfield stalwart McGregor levelled the scores with a drive from distance that took a deflection on its way in before further goals from Ryan Christie and Albian Ajeti had Neil Lennon's side comfortably ahead and in control of the match - until Julien Serrano pulled a goal back for Livi in the 78th minute with a rocket from 30 yards.

That ensured a nervy finish in which Livingston's debutant substitute Carlo Pignatiello missed a late chance for the visitors after failing to connect with a free header right at the death.

If Celtic can overcome Riga in Latvia, they will play FK Sarajevo or Buducnost Podgorica away in the one-legged play-off and McGregor is looking for a clean sheet to help them progress.

He told CelticTV: "We probably made it more difficult than what it should have been.

"At the start of the second half we look good, we look comfortable, get the third goal and then you probably fancy us to see it out 3-1 or 4-1 but I think that's something that we have to really work on, in terms of conceding goals.

"We're conceding too many goals as a team, shots from the edge of the box and things like that which is not really us. We have to work on that, we'll need to look at it and make sure going forward that we don't concede as many goals.

"We know what we need to do on Thursday. We look at this [Livingston] game, we have to learn from it quickly in terms of conceding goals.

"We go over there and put everything into the game and we are looking to get into that play-off spot, so everyone's looking forward to it."

The Scotland internationalist added that he was pleased to get his first goal of the season when he equalised minutes after Holt's opener at Parkhead.

He said: "I thought the boys reacted really well actually to the penalty.

"We got going and the ball fell to me, and I just took a touch and hit it. Sometimes they get a little nick when they go in which is fine, I will happily take that one."