Stuart Armstrong is already making a huge impact
After arriving from Dundee United in the January transfer window, midfielder Armstrong is already proving that Ronny Deila was right to pursue him. Armstrong followed up his debut goal against Partick Thistle last week with a quickfire double against Inter, and without him, Celtic would be out of this tie already. The second goal may go down as a Hugo Campagnaro own goal, but Armstrong willingness to get into the box led to both goals in a fine display.
Celtic can beat Inter at the San Siro
Before the game, we knew that Inter had been in decline ever since winning the 2010 Champions League, but Celtic have little to fear for the second leg. Mistakes from Jason Denayer and Craig Gordon led to two goals on Thursday night, and if Celtic can eradicate those errors in the second leg, they stand a great chance of going through - even having leaked three away goals.
John Guidetti still has a part to play
All of the talk surrounding John Guidetti in recent weeks has been about his goalscoring drought, having failed to find the back of the net since the 22nd of November. However, he came off the bench to land a vital last-gasp equaliser, and took his goal superbly well. The Swede may have his detractors, but he showed his class with that goal against Inter.
Celtic Park remains intimidating on big European nights
We've seen a number of clubs come unstuck at Celtic Park in the past; Manchester United and Barcelona have both been defeated in Glasgow, and the Bhoys fans proved again that no team would relish facing the Celtic crowd. They were vociferous throughout, creating a superb atmosphere - which ultimately helped spur the team on to the late equaliser.
The Europa League is not an also-ran competition
Ever since its inception, fans have been critical of the Europa League, saying that teams simply don't care about. That argument was put to bed at Celtic Park, with both teams desperate to win the game, producing a sensational 3-3 draw which you'd rarely see in the first leg of a Champions League tie. Both teams wanted to get into the last 16, and it sets up the second leg perfectly.