eil Lennon has told his Celtic players that there must not be a repeat of last season's European nightmare, according to Kris Commons.[LNB] The Irishman's first full season in charge of the Parkhead club began in depressing fashion last term as the Hoops were dumped out of the Champions League and Europa League at the qualifying stages by Braga and Utrecht respectively.[LNB]Commons can distance himself from that embarrassing and costly aberration having only joined Celtic from Derby in January.[LNB]However, the Scotland international has been included in the warning given to the Hoops players ahead of Thursday night's Europa League play-off first-leg tie against Swiss side Sion at Parkhead.[LNB]"Obviously it was a failure last year," said Commons, speaking at Lennoxtown where he was promoting ticket sales.[LNB]"I know I wasn't part of it but the manager has certainly made us aware that it can't happen again.[LNB]"He thinks we are a better squad than at the start of last year and thinks we are more prepared for Europe now so hopefully we can kick on.[LNB]"We know we are in for a tough test. We have to approach every game in a professional manner.[LNB]"You have to do your background and research on any team in Europe.[LNB]"I think the coaching staff and scouts have gone out and watched them so there are no changes on the night that we don't expect.[LNB]"We will now look at their qualities and weaknesses and hopefully we can capitalise on their weaknesses."[LNB]Commons will be playing in his first European tie, and added: "It's a completely different test and challenge for me.[LNB]"I will be coming up against some good players and in some tricky away fixtures but I just can't wait for the game at Celtic Park.[LNB]"A lot of people have spoken about European nights at Celtic Park and that's something that I want to play in."[LNB]Despite a naturally positive disposition, Commons would not be persuaded to claim Celtic could go all the way to the final.[LNB]"It's a little too early to say that at this minute," he said, straight-batting the question.[LNB]"We went out pretty poorly last year so it's important that we can improve on that, get to the group stages and start making small steps instead of thinking about the final.[LNB]"I think that's way off at the moment.[LNB]"So there are no set targets, it's just to get as far as we can."[LNB]Celtic's most recent financial results were revealed on Monday and showed how important European football is to the Parkhead club.[LNB]The 14.8% decrease in turnover to £52.6million was, in part, due to the absence of an extended run in Europe.[LNB]However, Commons insists that will not add any extra pressure to the players on Thursday night.[LNB]"It's not something the players think about," he said.[LNB]"As a footballer, it's important that we concentrate on the job in hand and that's playing football.[LNB]"And hopefully, if we can get through to the group stages, more royalties will come our way."[LNB]Meanwhile, midfielder Ki Sung-yueng joked that he was too tired to enjoy his goal in Saturday's 5-1 win over Dundee United at Parkhead after travelling back from Japan where he had played in South Korea's 3-0 defeat in an international friendly.[LNB]He told the club's official website: "I was seeing two footballs at times. I can't even remember what my goal looked like because I was too tired.[LNB]"There was such a big time difference that when I played the game it was actually time for me to sleep.[LNB]"I didn't expect to get a full game but it is a privilege to play, especially at Celtic Park, so I had to keep going, I was never going to ask to come off.[LNB]"The couple of days rest at the start of the week will do me good because then I will be ready again for Thursday.[LNB]"We all want to play in Europe and we have to show we are capable of doing that.[LNB]"It will be great experience for all of us if we qualify.[LNB]"There is a big difference because we have been together for a year now and we all know each other better."