It was a game long anticipated by Liverpool supporters, a return to the top tier of European football for the first time in more than 16 years.Yet when the Reds made their bow in the Champions League proper, there were almost 15,000 empty seats inside Anfield.A famous European night it was not.But historians pondering such a curiosity would be well served taking a glance at the date of that opening group game against Boavista.September 11 2001.Exactly 20 years ago today, Liverpool made their first appearance in the revamped European Cup just hours after the terrorist attack on the World Trade Center in New York.READ MORE: Jurgen Klopp sends warning after FIFA ban Liverpool playersJoin the Blood Red Club to unlock EXCLUSIVE podcasts and videosWant more of our Blood Red podcasts?Then join the Blood Red Club to receive exclusive content direct to your inbox every week - and it won't cost you a penny.Sign up here - it only takes a few secondsThese were uncertain, troubling times, with the much of the Western world concerned over potential ramifications and any subsequent threats.And, certainly, there were a significant number of supporters - those already with tickets and others who were planning to pay at the gate - who chose to stay at home and watch the latest breaking news on television.The attendance of 30,015 must be put into some context, though, with the second home group game against Dynamo Kiev a month later attracting only 33,513.But the Boavista crowd was smaller than the 31,000-plus who watched the second leg of the August play-off against Haka where Liverpool were already 5-0 up. Ignoring games played behind closed doors, it remains the lowest crowd for a Champions League game at Anfield.Those who did turn up were hardly treated to a classic.In an unsurprisingly surreal, subdued atmosphere, Liverpool fell behind in the second minute when they failed to clear a long ball by Boavista goalkeeper Ricardo, and Elpidio Silva fired home after exchanging passes with Alexandre Goulart.Sign up for daily Liverpool newsGet all the latest Liverpool breaking news, team news, transfer rumours, injury updates plus analysis of what's next for the Reds.You'll also get the latest transfer talk and analysis every day for FREE! Sign up here - it only takes a few seconds!The Reds levelled just before the half-hour when Michael Owen curled a fine effort into the top corner having been found by Steven Gerrard.But apart from one save from Jerzy Dudek - making only his second appearance having signed from Feyenoord - and a couple of half-chances for Owen, that was about it.Not that Boavista coach Jaime Pacheco was too happy, saying Liverpool "savaged" his players despite the Portuguese side picking up seven of the game's eight bookings."I came to Liverpool to play football, not rugby," said Pacheco. "Our players are less physical, less endowed and they were savaged."The referee seemed to be on the side of Liverpool."Houllier, though, was having none of it."When we played in Rome and Barcelona last season we were never accused of being over-physical," he said. "The demands of this competition are that you are strong and physical - that's what we were."Emile Heskey of Liverpool charges through during the UEFA Champions League Group B match against Boavista played at Anfield on September 11 2001 (Image: Alex Livesey/Allsport)The reality is, though, the game shouldn't have been played, UEFA finally seeing sense the following morning and cancelling the week's remaining European ties out of respect for the victims of 9/11 and in light of the continued security concerns across the globe.Liverpool eventually progressed through the group thanks to a final matchday home win over Borussia Dortmund, before doing the same against Roma in the oft-forgotten second group stage.A shock 4-2 defeat at Bayer Leverkusen in the quarter-final second leg - where Liverpool were within six minutes of progressing - ultimately proved a turning point under Houllier, who had not long returned to the dugout having been absent for five months after undergoing life-saving heart surgery.Boavista? They were eliminated in the second group stage and have failed to qualify for Europe since reaching the UEFA Cup semi-final the following season.The Portuguese championship triumph that earned them their place in history against Liverpool remains their only national title. And should they turn up at Anfield again in the Champions League, they can perhaps expect to do so in front of a larger crowd.Read MoreRelated ArticlesRead MoreRelated Articles