RONNY DEILA watched St Johnstone end his club's eight-game clean-sheet run, and threaten to bring to halt their seven-match winning streak into the bargain.

But the Celtic boss reckons Saints did his players as favour as they provided the kind of test they needed ahead of Thursday's Europa League last-32 tie against Inter Milan.

The SPFL champions have been in such imposing and impressive form since the turn of the year that they were in danger of cruising into this week's first leg - and suffering a rude awakening as the quantum step-up in class hit them.

Taking another very early lead, through Leigh Griffiths with only 35 seconds on the clock, made it appear even more likely Celtic would, once again, stroll to three points without being extended.

However, St Johnstone showed none of the fear which other opponents have displayed when faced by the free-wheeling Green Machine in recent weeks.

With Celtic so quick and adept in transition, their counter-attacking prowess has caused teams to sit deep and not commit because they are so concerned about being picked off.

St Johnstone elected to have a go, and got their reward when Michael O'Halloran was on hand to ram home a goal after Craig Gordon could only push out Chris Kane's close-range effort.

Cue a late charge for an equaliser, but Gordon proved unwilling to concede again, one double save from a Brian Graham header then Dave Mackay's rocket follow up underlining why the comeback keeper is a strong candidate to be Player of the Year.

His heroics allowed Stefan Johansen's neat finish just after the break to prove to be the winning goal.

But, despite enjoying a much-less relaxed 90 minutes in the dug-out than he has been accustomed to, Deila still liked what he saw from his Bhoys.

And his belief that they are ready to meet Inter head on is undiminished.

The Hoops boss reckons it was a reminder of the standard they have to maintain and said: "I think it was a good time to have a test like that.

"But the problem we had was we lost the ball too much.

"We need to be better on the ball, and that is what we are working on every day.

"We have our way of playing, and, when we do that over and over again, you will always improve."

There does have to be an element of adaptation, however, as Deila explained: "The pitch was not great at Perth.

"But I think it is good for Scottish football, as well, that other teams attack us so that we get good games."

Despite his laid-back reflections, tempered no doubt by the fact he had just seen his side go six points clear in the title race, Deila will be at pains to point out to his players that, if they are as negligent in possession against a side of the quality of Inter, they will be punished far more severely.

"There's no doubt we will have to be more accurate with our passing against Inter Milan," said Deila, who is looking forward to experiencing his first full house since he became Celtic manager in June.

The stadium almost sold out for the visit of Maribor in the Champions League play-off, but the fans left bitterly disappointed after the Slovenians won to go through to the Group Stage.

Deila wants to utilise the fan power to better effect this time.

He said: "The fans are very excited about the fact it is Inter this time.

"But for this game, like every other, we have to keep the same mindset, and try to put out a team to play to the best of our ability.

"We are at home, and we have a duty to try and entertain the fans."

The history between Celtic and Inter has been played out at a much higher level than the last-32 stage of Europe's secondary competition.

But it is where both clubs are at the moment, the Hoops having failed to negotiate the qualifier and play offs for the Champions League, and Roberto Mancini's side struggling to compete for the title in Serie A.

For all of that, this remains a hugely glamorous match up, though the fundamentals behind having the chance to make it through to the next round are the same as they are for any match.

Celtic have certainly looked better equipped to compete at this level since the turn of the year.

The manner in which they fell away in the latter ties of the Europa League Group Stage, losing to Salzburg and Dinamo Zagreb, did not auger well for this Last 32 test.

But the run they are on indicates a corner has been turned, and that they can give a troubled Inter side a run for their money.

Deila accepts they must tighten up in a few areas, however, not least defending the ball in the air.

St Johnstone players got their heads to too many crosses for the manager's liking, and Deila acknowledges Inter are a much more imposing side than Saints when it comes to aerial threat.

He admits it is a concern his side is not as dominant as it should be when the ball is flying across their area and said: "We have to work on this and become better at defending this in the box.

"But, if you take set plays over the season, we have been very, very good.

"We have only conceded two goals from this and scored 13 or 14 (from set-plays)."

If any of his players can pop up with a goal from a corner or free-kick against Inter, it will be further proof all the hard work Deila and his coaching team have been doing with the squad has been worth the effort.

If they can continue their opening-minute strike rate, it will be even more appreciated as it will settle nerves in what promises to be a real test of character.