Magnus Carlsen has lost an amazing! game

Norway's 24-year-old chess phenom, Magnus Carlsen, successfully defended his World Chess Championship late last year in Sochi, Russia, once again defeating 44-year-old Viswanathan Anand of India.

But that doesn't mean Carlsen is unbeatable, as we just learned.

On Monday at a big and very important tournament, the Tata Steel in Wijk aan Zee in the Netherlands, Carlsen went down to the Polish number one, Radoslaw Wojtaszek.

Wojtaszek is 28, a Grandmaster, but rated 2744, more than 100 points lower than Carlsen, 2862 (who has the highest rating of all time).

Interestingly, however, Wojtaszek was one of Anand's "seconds" for the World Championship - effectively, a sparring partner and assistant to the challenger. Of course, this means that at the moment, Wojtaszek knows Carlsen's game as well as anyone on Earth.

On Monday, it showed.

At the WCC, Carlsen indicated that in dynamic positions, he can leave open the prospect for tactics - combinations of moves that are the heart and soul of attacking, "fighting" chess, but that in the modern game occur less frequently than in the past, due to players' ability to train with computers and avoid complications.

In their game, the third of 13 scheduled, Wojtaszek was playing white and created a beautiful tactic on move 40.

As you can see from the diagram below, Carlsen, as black, is on the attack with his pieces converging on Wojtaszek's king. But earlier Wojtaszek had captured a bishop for a pawn, and he finds a way to convert that to a decisive advantage by trading queens.

Can't take the f5 pawn with check...

To avoid the loss of his f-pawn - and a check - by the white king, Carlsen slides his king to the g7 square. But then Wojtaszek plays for the queen exchange with the move Qf4, Carlsen takes with his queen, and then Wojtaszek "forks" the black queen and king by playing his knight to h5 with check....but his queen and king are then "forked" by the knight!

Carlsen has to get his king out of check, so Wojtaszek picks up the black queen on the next move.

A bit later, he threatened to snap up another black pawn, so Carlsen resigned on move 52. Wojtaszek's extra piece would enable him to win the endgame.

So, a very pretty win - although analytically, perhaps lost several moves before the decisive queen exchange. Carlsen had already kind of quasi-blundered his queen into an ill-advised attack.

Carlsen did win his game in round 4, so it's not like he's completely falling apart.

Meanwhile, Carlsen's main rival these days, Italy's Fabiano Caruana (actually, an American who now plays for Italy) is having another solid tournament, surging into first at the Tata Steel before being displaced by Vassily Ivanchuk, an unpredictable, aging Ukrainian genius called "Big Chucky" on the international chess scene.

Caruana laid waste to an impressive field (including Carlsen) in St. Louis last year before the WCC and is now the odds-on favorite to challenge Carlsen for a future title.

He's a cerebral 22-year-old who lives and breathes chess and has stormed the top ranks of the game over the past two years.

It looks like 2015 is going to be an impressive year for big-time chess, as Magnus battles to stay on top and literally everyone take a crack at beating him, including some impressive young players, along with a few veterans.

You can review the entire Wojtaszek-Carlsen game at ChessBase.