It's White to play. Alan played 27. Qc4! Not an obvious move, but one that Stockfish likes a lot. The immediate threat is 28. Rf5, which wins a pawn. Justin played 27... Qd6?!, threatening the g3 pawn. Alan pressed ahead with 28. Rf5, and after ... Qxg3, 29. Bxc5 Qe3+ 30. R1f2, White is +3 on the computer.
The game ended with Alan having a queen and three pawns against Justin's queen. You can view the game on the ChessBomb site.
Alan has a dream draw tomorrow in Round 5 when he will play Black against tournament favourite and top seed Michael Adams. The game starts at 13.30.
Ed Player and Dagne Ciuksyte are on 1½ points out of four.