This is the only decisive game of the round, all the rest were drawn.
See the summary of the results of Round 4 in the following table:
Replay the games of Round 4 below: [replay]
London Chess Classic 2016 Ranking after Round 4
With this win, Nakamura was able to catch up among the leaders with 2.5 points, just half a point behind the sole leader, Wesley So. Remember that in order for Nakamura to topple So in the Grand Chess Tour title race is when the former gets to be the champion in the London leg and the latter to rank lower than 3rd place.