CELTIC are closing in on the £3m signing of Rapid Vienna left-back Boli Bolingoli-Mbombo, and he could even be added to the squad in time for the Champions League qualifiers.

The deal moved closer as it was understood that Napoli have edged in front in the race to sign first-choice left-back Kieran Tierney.

READ MORE: Scottish transfer news LIVE: Lennon confident of Mbombo signing | Lafferty to Thailand? | Tierney latest

Celtic manager Neil Lennon says he hopes to have the deal over the line before the deadline for registering players for the Champions League passes on Thursday, with the 23-year-old on the verge of agreeing a deal to join the Scottish champions.

“We are not too far away, and he will be another good addition to the squad,” said Lennon.

HeraldScotland:

READ MORE: Celtic defender Marvin Compper quits Parkhead to join German side Duisburg

“He gives us competition at left back, he’s strong, athletic and good on the ball.

“He fits the criteria and hopefully he’ll be in before Thursday.”

Despite the arrival of Bolingoli-Mbombo, Tierney remains a Celtic player, with the club receiving no fresh bids for their first-choice left-back since a £15m offer from Arsenal was rejected last week.

Lennon admits though that the speculation has become unsettling for the 22-year-old.

“As I said last week, the first offer wasn’t what we’d look for and I don’t think we’ve had another one yet,” he said. “It’s as you were. Will it rumble on? Probably.

“These things take their course whether it happens or not. We have a price for our player. He’s on a long-term contract and we won’t sell him for anything less than we feel is the right price.

“It can be unsettling, but he’s been okay. He’s not really training with the group but hopefully we’ll see him on the training ground in a week or two.

“In terms of where he is mentally, it’s got to be unsettling for him, it’s only natural.”

Lennon was speaking after a goalless draw with St Gallen brought the curtain down on their pre-season tour of Austria and Switzerland, with Jozo Simunovic sent off for Celtic with 15 minutes to go for a high boot on opponent Boris Babic after a VAR review.

HeraldScotland:

READ MORE: St Gallen 0 Celtic 0: Jozo Simunovic sees red as Celtic held in Switzerland

Celtic were trying to find out last night if the centre-back would face a suspension for the offence, and it is understood that referee Fedayi San will report the incident to the Swiss FA, who will in turn inform the Scottish FA. It will then be up to the SFA to decide whether to take any disciplinary action, but it will not affect the Croatian’s availability for the Champions League qualifiers.

A Celtic side thumped St Gallen’s under-21 team earlier in the day, with Leigh Griffiths continuing his hot goalscoring form since his return to the fold, netting four in a 9-1 win.

Scott Sinclair scored a double, Ewan Henderson got one, as did Lewis Morgan, while Karamoko Dembele also got himself on the scoresheet.

Meanwhile, Marvin Compper has finally left Celtic to join German third-tier outfit MSV Duisburg. The German defender, who played just 83 minutes in a Scottish Cup tie against Morton in 18 months at Celtic Park, left by mutual agreement after having his lucrative contract terminated.

“That one was probably best for both parties,” explained Lennon.

“He wasn’t going to fit in our plans, so it was best he moves on and we can fill a gap now.”