Celtic's passage into the knockout phase of the UEFA Champions League was as unlikely as it was exhilarating and watching the scenes of unbridled joy in the Parkhead terraces as the Bhoys put Barcelona and Spartak Moscow to the sword was enough to make even the harshest critics of their defensively-minded play smile. For Neil Lennon and his team however, it means two extremely tough matches against a Juventus side brimming with confidence, however if Celtic can recall the spirit shown in their previous two trips to the knockout rounds allied to their hard-working ethos and defensive stability, there is every chance they could come out with a positive result.
In 2006-07, the Bhoys were placed in a group with Manchester United, Benfica and FC Copenhagen, and were widely expected to drop into the UEFA Cup by virtue of finishing behind the United and Benfica. Gordon Strachan's Celtic in those days were not short of quality, boasting full internationals such as Jan Vennegoor of Hesselink, Jiri Jarosik, Shunsuke Nakamura, a still-raw Aiden McGeady and Gary Caldwell, who has gone on to since show himself as a solid presence in the English Premier League.
Their opening encounter was at Old Trafford, and although Vennegoor put them ahead, they eventually succumbed 3-2 in a ding-dong battle. The template for Celtic in Europe has long been home victories and away losses, and this was to continue, a 1-0 victory over Copenhagen was tempered by a 3-1 loss in Denmark, and a 3-0 home win over Benfica was countered with a reverse of the same score at the Estadio da Luz. The highlight was the 1-0 victory over United at Parkhead, Shunsuke Nakamura's stunning free-kick ensuring all of the points. Their perfect record at home was enough to put them into the last 16 for the first time in the Champions League era as runners-up to United.
Whilst fingers were crossed for a draw against Lyon, arguably the weakest of the group winners, the balls were not kind and they drew eventual champions AC Milan, a side with massive experience boasting the likes of Clarence Seedorf, Paolo Maldini, Filippo Inzaghi and Kaka, who was well on the way to proving himself as the best player in the world at the time. The first leg was a tense affair, Milan easily dominating the ball, but failing to create many meaningful opportunities. Celtic 'keeper Artur Boruc was the hero, saving well from Alberto Gilardino.
The return leg at the San Siro saw Milan turn the screw even more, but Boruc and his centre-back pairing of Stephen McManus and Darren O'dea managed to keep the Milanese hordes at bay. After 180 minutes, the tie was still level which meant extra time, however just three minutes into the added period, Kaka displayed why he would go on to win the Ballon d'Or, bursting forward from midfield and calmly finishing to break Glaswegian hearts and dump Celtic out of the competition.
The following season, they entered the competition with the confidence of having taken the eventual winners to extra time. The group draw gave them Shakhtar Donetsk, Benfica and in a delightful twist, the chance to take revenge on Milan. Celtic's group stage template continued, losing their opening encounter 2-0 to Shakhtar in Ukraine before bouncing back with a famous 2-1 home victory over Milan, Scott McDonald's 90th minute winner laying to rest the ghosts of the previous season's San Siro heartbreak. Victories over Shakhtar and Benfica were again enough to send the Bhoys through on nine points and this season they hoped for a more favourable draw.
This was not to come however, as the lottery gave them a tie against FC Barcelona. Whilst this was pre-Guardiola, the side had the beginning of the team we came to know as the greatest in the world in following years. A terrifying forward line of Lionel Messi, Thierry Henry and Ronaldinho would test the Celtic defence to their limit and beyond. Barca took control of the first leg at Celtic Park right from the off, with only 19 year-old debutant Paul Caddis's goal-line clearance sparing a goal in the opening 10 minutes. Celtic however, managed to take a shock lead, Jan Vennegoor of Hesselink rising superbly to get on the end of Lee Naylor's cross and sending Parkhead into raptures. This was short-lived, Messi equalising just two minutes later however Celtic sensationally went ahead again, Barry Robson's looping header giving himself a debut to remember and giving the Hoops a half-time lead. In the second half, Barcelona's relentless pressure told as Thierry Henry scored a delightful equaliser, before Messi's winner with 10 minutes to play sent the Celtic fans home disappointed.
The return leg was effectively killed off after three minutes, Xavi Hernandez putting the home side two goals up in the tie. Barcelona were then able to relax and pass the ball around their opponents, and whilst Celtic occasionally pressed for an equaliser, Barca comfortably saw the tie off. Two years, and two difficult draws for Celtic however there was no shame in their spirited displays on either occasion.
2007-08 was to be a high watermark for Scottish football in Europe. Along with Celtic's passage to the knockout rounds, Rangers battled and blocked their way to the UEFA Cup final whilst Aberdeen made it to the last 32 of the same competition, stunning Bayern Munich to take a 2-2 draw at Pittodrie before succumbing to their illustrious opponents 5-1 in Germany. Since then, things have gone somewhat awry for the Scottish game. Celtic and Rangers made the group stage of the Champions League in the two following years but neither managed to trouble the qualifiers, and until this season, no Scottish side had passed the qualifying phase since 2009-10.
Ironically, the decline of the Scottish game may be the very reason Celtic have performed so well in Europe this season. Rangers' financial meltdown and subsequent demotion to Division 3 has meant that the Hoops have no realistic domestic challenge. This has given Neil Lennon the freedom to always have his best side prepared for their midweek encounters, and this has told in the energy and workrate of the entire side, particularly in the famous victory over Barcelona, whilst the goalkeeping heroics of Fraser Forster and inspired displays of forward play from Georgios Samaras can't be underestimated. It is this energy that they will need to call upon against Juventus, who have in Andrea Pirlo a player who can pick even the heaviest of locks. A little of the spirit of '07 and '08, a little of the energy of the Barcelona ties from this season and a keen eye on Pirlo may just be enough to see Celtic through to the last eight of the competition.