INTERNAZIONALE may not be the all-conquering colossus they once were but Celtic will likely discover this evening that they remain a force to be reckoned with.

These are testing times for the three-time European champions. Without a trophy to their name since 2011's Coppa Italia success, the years since Jose Mourinho's impressive treble haul in 2010 have been largely unremarkable. Managers have come and gone without barely causing a ripple; Rafa Benitez, Leonardo, Gian Piero Gasperini, Claudio Ranieri, Andrea Stramaccioni and, until last November, Walter Mazzarri have all endured reigns of disparate lengths but similar levels of ordinariness. There has been a period of sizeable financial downsizing - prompting most of the Champions League-winning squad to move on -a change of ownership, as well as numerous personnel and tactical switches. All have been to little or no avail.

It is perhaps Celtic's misfortune, then, that Inter arrive in Glasgow this week as buoyant as they have been for quite some time. The return of Roberto Mancini as manager has lifted spirits noticeably, even if there have been inevitable bumps and setbacks over the past three months as he tries to put his plans into place. The club has changed dramatically since Mancini's first spell as manager - when between 2004 and 2008 he won seven trophies, including 3 Serie A titles - but his ambition remains undiminished. He has been busy since leaving the San Siro seven years ago, delivering Manchester City's first title for 44 years and a cup for Galatastary, and there are already signs that he will not stint in his desire to restore Inter to former glories, if his bid to recruit Yaya Toure from City in the summer is anything to go by.

Mancini's arrival came too late to salvage the season domestically. Inter, like their neighbours Milan, find themselves in mid-table in Serie A, 22 points behind leaders Juventus, and already out of the Coppa Italia. Europe is all they have. A Europa League title would sit nicely on the roll of honour for the three-time UEFA Cup winners and, perhaps more importantly, grant them access to next year's Champions League. For financial reasons as much as prestige, that could be vital in helping realise Mancini's ambitions.

To that aim, he was busy in the January transfer window. Xherdan Shaqiri , the dangerous and pacy Swiss forward, arrived from Bayern Munich, while Davide Santon was brought over on loan from Newcastle United, a return for the 2010 treble winner. Lukas Podolski was also signed from Arsenal and Marcelo Brozovic, who scored against Celtic earlier in the season, came from Dynamo Zagreb, although both are ineligible for this competition.

Things are gradually starting to click for Inter. A 3-0 victory over Palermo was followed on Sunday by a 4-1 win over Atalanta, the first time the team had won back-to-back matches since Mancini took over. In Mateo Kovacic, the young Croatian hailed as the new Pirlo, Colombian Freddy Guarin, and Mauro Icardi, the prolific if slightly unhinged Argentinian striker, Inter have players capable of causing serious damage to Celtic's own European aspirations. Little wonder Mancini cut a quietly confident, if deferential, figure as he took a seat inside the Jock Stein lounge to assess his team's chances of prevailing at Celtic Park in the first leg of the teams' last 32 tie on Thursday night.

"I'm proud to be Inter manager it this match and it will be a great event," he said. "Maybe we have lost this kind of atmosphere in recent years - playing in front of 60,000 fans. But I will be more proud if Inter beat Celtic.

"This competition is very important for us, although we know the Europa League is a difficult tournament. Personally, I'd like to win it for many reasons but we have to take it one game at a time. There are four more rounds after this one. I think all the teams left in the competition at the moment will be trying to win it."

From Celtic's perspective this tie has also offered up an opportunity to reminisce about the time they put Inter to the sword 48 years ago to win the European Cup. The significance of the rematch, however, was lost on Andrea Ranocchia.

"I don't have any thought s on 1967, I don't even think my dad was born then," smiled the Inter captain. "But big matches like this are always a great experience."

Mancini, impeccably-attired in a club blazer over the top of the sort of wide-collared white shirt usually favoured by Harry Hill, could not have been more courteous towards his hosts. He rebutted the suggestion that Celtic would pose a more physical threat than is usually the case in domestic matches, believing this will be a contest decided on craft rather than graft.

"Celtic are a good team," he added. "They play good football, they don't play long ball as they have good technical players. Scottish football has improved a lot in the last few years and it's good that Celtic play this way. They can progress if they play good football and I am not surprised that they have this style.

"I think Scottish football has improved a lot in the last years. And it is better for them to play like Celtic play at this moment. In the end, you can win by playing good football." Mancini will be hoping the same applies to his team, too.