Celtic are weighing up a move for £3million-rated Rapid Vienna left-back Boli Mbombo.
And despite seeking a fee in excess of £25m for the Scotland international, Celtic are scouring the market for potential replacements.
Rapid Vienna left-back Boli Mbombo has attracted interest from Scottish champions Celtic
Ecuador Under-20 midfielder Jose Cifuentes is also a £2.5m target.
The 20-year-old, who plays for America de Quito in his homeland, is being tracked by Manchester City as well as clubs in Germany and Italy.
Wage demands have reduced the chances of a move for Romain Perraud after Neil Lennon flew to Paris to scout the Nice defender.
Kilmarnock’s Greg Taylor is also on a list of targets despite interest from Rangers, Hull City, Wigan and Middlesbrough. Sportsmail, however, understands Celtic have developed an interest in Belgian-born Mbombo.
A cousin of Belgian striker Romelu Lukaku, the 23-year-old joined Rapid from Club Brugge two years ago, but is set to leave the Austrian club this summer.
Huddersfield and Burnley have also been credited with an interest.
Tierney, 22, recently had a double hernia operation after the Scottish Cup final, but hopes to be fit in time for the new season and will fly out with the rest of the squad to Austria.
Celtic are eyeing replacements for Kieran Tierney, who is the subject of interest from Arsenal
Serie A side Napoli also enquired over his availability and, with life-changing wages on offer, the full-back’s advisors believe the time is right to take the next step in his career. Midfielder Callum McGregor, a target for Brendan Rodgers at Leicester City, is likely to stay put.
But Celtic are willing to sell Olivier Ntcham to Marseille, with the £14m asking price the obstacle to a deal.
The £3m signing of Motherwell’s David Turnbull should be completed after a medical in Manchester over the weekend but Lennon is keen to add six new players before the season begins.
Both Celtic and Aberdeen have dismissed reports of a £5m bid for Scotland central defender Scott McKenna. However, the Parkhead club have an interest in £7m-rated Toulouse defender Christopher Jullien, while Danish international right-back Peter Ankersen is also a £2.5m target from FC Copenhagen.
Meanwhile, Karamoko Dembele joins the Celtic first-team contingent heading to Austria. And the 16-year-old is keen to build on his top-team breakthrough by forcing his way into Lennon’s plans on a regular basis.
Dembele was handed a debut in the final Premiership match of the season in the 2-1 win over Hearts at Parkhead.
Burnley and Huddersfield are also interested in 23-year-old Mbombo this summer
Speaking to Celtic TV, he said: ‘It was unbelievable because I wasn’t really expecting it.
‘When I was coming on everyone was singing my name and it was crazy.
‘It was quite hard not to smile but it was really nice, to be honest. As soon as I got on the pitch, I just never wanted the game to finish.
‘Now I’m looking forward to this season to hopefully get another chance. It was something to look forward to.
‘Then finally getting to do it, was kind of a relief.
‘This season is just about focusing on getting in the first team and getting as many opportunities as I can.
‘Doing it in training and proving it in games as well, just be relentless with it.
‘There’s been a lot of attention and a lot of pressure but I’ve dealt with it well to be honest, with me and my family and everyone helping me to just focus on football.’