Barcelona had a chance to win its fourth game in Group G and guarantee a spot in the next round. Instead, it lost to Celtic, 2-1, and hasn't guaranteed anything just yet.
And yes, you just read that correctly—Barcelona lost to Celtic. Good luck wrapping your head around that one.
Give credit where credit is due—Celtic played an excellent game and earned its three points and historic win. But there's not doubt that the Catalans will regret failing to perform.
Behind Lionel Messi, Barcelona simply failed to capitalize on its many chances. Messi and Alexis Sanchez hit the woodwork. The pair each had several nice opportunities go wanting, Messi especially. Dani Alves was a force down the flank, but couldn't translate it into a goal. Xavi and Andres Iniesta each pushed shots high.
Of course, Messi would eventually get himself a goal in stoppage time after a deflection and scramble up front, but it was too little, too late.
Obviously, Messi and Barcelona had countless opportunities in this game. The Catalans pushed the Celtic defense to its very limit, but couldn't crack it, in large part to Fraser Forster's inspired effort in the contest.
Barcelona still leads the group with nine points and only needs a tie to ensure it will advance, but it could have erased any doubts about advancing to the quarterfinals and essentially rested its regulars over the final two games of group play.
It was an opportunity wasted. And it raises several questions about the Catalans.
Does the side need to start adjusting some of its tactics, especially when it seems like its style of attack is playing right into the opponent's defensive strategy? Is the imposing and intimidating Barca starting to show some cracks in the armor, leading opponents to play against it with more confidence?
Honestly, I would say no to both of the above. Barca—and Messi especially—had plenty of chances, it simply failed to execute them. This is just one game, and at Celtic's home stadium—never an easy place to play.
I don't think we should read much more into it than that.
This will long live on as an evening to remember for Celtic. For Barcelona, the bitter taste of an opportunity gone wanting will linger in the present, but ultimately will best be forgotten about.
Lionel Messi and Barcelona will have better days than this. I pity Benfica and Spartak Moskva after this result.
Hit me up on Twitter—my tweets aren't afraid to get emotional after a big win.