Below, I will provide some sort of liveticker to keep you updated.

Game 1 of the four game rapid tiebreak ended peacefully after Sergey once again did not achieve anything against Magnus’ Berlin Defence. After some unusual setup in the Berlin simplifications started soon leading to an equal endgame. Sergey continued playing for some moves with regard to the isolated Black pawn on e6 that gave White the easier play. Magnus did not lack accuracy though and a draw was agreed soon.

Game 2 without any doubt was by far the most thrilling game we’ve seen in the whole World Championship match! Sergey with the Black pieces quickly got into trouble after the opening and decided to give two pieces for rook and pawn. Magnus could easily consolidated and win back the pawn thus reaching a technically rather easily winning endgame.
However, for some reason Magnus decided to exchange queens making his task to convert a lot more difficult while respected endgame experts like GM Georg Meier even evaluated the position with rook vs. bishop with three pawns each on the kingside as draw. With seconds left on the clock Sergey indeed offered another chance for Magnus to win the game but finally miraculously hold the position by reaching a theoretically drawn endgame with pawn vs. bishop + two pawns.

Still shocked about what I just saw!

Game 3 sees another Berlin where Magnus with the Black pieces early pushes his f-pawn to f4 where it gets blocked by Sergey’s f3 which is critizised by Svidler as an unnecessary weakening. Magnus seems on fire sacrifizing another pawn while getting dominant play with a strong knight vs. bad bishop and the open a-file to penetrate with his rook. Sergey once again relying on his defensive skills.
In an objectively equal position but huge playability advantage for Black it finally happens: Sergey blunders and immediately has to resign. First time for Magnus to take the lead in the match!

Before the fourth and last rapid game all trumps are on Magnus side. With a draw in his White game he would be the remaining World Champion! Can Sergey strike back? How will he able to put pressure on Magnus?

Game 4 sees Sergey playing Najdorf indicating he is ready to go for the full point. Magnus on the contrary, replies with a solid setup including f3 and c4 knowing he is not the one to take any risks. His follow-up makes a well impression, too. These kind of positions are in his favour since he can start manoeuvring his pieces while using his amazing intuition before finally changing the type of position. Tough task for Sergey who is currently defending a position. Generally speaking Black’s position potentially  does allow active ideas at a later stage though using the a-file and given the weakened White king.
Magnus has the dominant and probably winning position. However, there is still a way to go since Black stil remains with counter attacking chances due to the abovementioned. Don’t forget how Sergey managed to come back in several games in the Candidates and you know it’s not the time to throw the towel!

Magnus now on the verge of converting. He won the exchange while Sergey remains with his bad bishop f8. We’ve seen a lot just today but I really can’t imagine Magnus to spoil this.

White is clearly winning now with Sergey desparately trying to avoid the inevitable.
Oh my god!!! Magnus finishes off the game in an remarkable style mating Sergey with an epic queen sac!

Congratulations Magnus!
He clearly wins the rapid tiebreak 3-1 and basically did not leave the slightest chance to a hard fighting Sergey who today seemed not being able to continue his solid performance he showed in the classical games. However, big respect to Sergey who actually was pretty close to win the title himself in the classical games!