Neil Lennon is wary of the threat FC Sion will bring to Parkhead in the Europa League play-off first-leg on Thursday, having once lost to Swiss opposition in Europe with Celtic before.

He was part of the side that was knocked out of the Champions League qualifiers by FC Basle in 2002, a result that still irks him. But if there is a reflection of the nature of the tie, it can be found in the opinions of Ramon Vega and Michael Silberbauer.

The former once played for Switzerland and Celtic, so his view is shaped by the size and stature of the Parkhead side and he believes that they will have “nae bother” in progressing; the latter plays for Young Boys Bern, who faced Sion in the league recently, and warned of the danger of underestimating Swiss football.

Sion are a technically accomplished side, and ambitious enough to have signed six new players during the summer (who should be available on Thursday even although Fifa dispute their eligibility), but do not have the size of following or historical prestige of Celtic.

It is a classic European tie, pitching a big club against a smaller one, but with both coming from leagues that are comparable. The general expectation is for Celtic to reach the Europa League group stages, but it is not an easy assumption to make; their opponents will be adept and shrewd.

“Sion are improving all the time but Celtic have more quality in their squad,” says Vega, who now works as a financial advisor in London. “In the past, Sion normally struggled in the Swiss league, but they have got better in recent years. They have a lot of talented young players and a few good foreigners. I don’t think Sion should be underestimated, but I would be very surprised if Celtic didn’t go through. The standard of Swiss football is quite similar to Scotland, but there are no clubs like Celtic, [who] should be too powerful for Sion.”

Silberbauer has twice faced Celtic in Europe, with FC Copenhagen and then FC Utrecht last season, and on both occasions suffered defeat at Parkhead but won the tie overall. He describes Sion’s Stade Tourbillon as capable of generating an “intimidating atmosphere” and believes that Celtic need to establish a commanding lead from Thursday’s first-leg at home.

The Danish internationalist identifies Giovanni Sio, an attacking and goalscoring midfielder, and Goran Obradovic, the captain, as the key creative influences. Young Boys defeated Sion away 2-1 last month, but Silberbauer points out that the scoreline owed much to the home side twice hitting the post and missing other chances.

“They are a strong team,” he says. “It will be a hard test for Celtic to get through. People can still underestimate Swiss football. There are a lot of good teams in the league. It’s maybe comparable to the teams in the Netherlands -- if you took Ajax away. The standard is strong. You saw the Swiss national team doing well against England recently and there has been a big push in the country to improve standards and bring through youth players. They are trying to build a new talent base and were runners-up behind Spain in the European Under-21 Championships this summer. It’s a country going forward and Sion are part of that.”

Vega was a team-mate of Lennon’s at Celtic Park, and although the Swiss defender only spent six months in Glasgow in 2001, he won the treble. The club “will always be in my heart,” and Vega is certain that Lennon will benefit from having worked under Martin O’Neill.

“Did I see Lenny as a future Celtic manager? Not really,” he says. “But people change as they get older-- they mature and gain more experience. Lenny has the character to be the Celtic manager because it is not an easy job. He also worked under one of the best managers Britain has ever produced in Martin. He is young but I think he deserved to be given a chance to manage Celtic after everything he achieved as a player. He is doing well so far and I wish him all the best for the future. I hope he stays at Celtic for a long time.”