Impressive Defence

I WAS under the cosh for much of the middlegame playing for Battersea 2 against league-leaders HMC in division one of the Central London League last night.
But I held on, and in the diagram below have just played 45.Nd4-e6, with threats of penetrating with my queen, eg 45...Kf7? 46.Ng5+ Kg8 47.Qb6, when White has a very strong attack (Black can check on f1 but the White king will be perfectly safe going to h2).

Can you find Black's best move in Spanton (171) - Andrew Gilfillan (186)?

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45...d4!
My main analysis engines, Stockfish10 and Komodo9, agree this is Black's best defence, reckoning the pawn sac gives Black full equality. The point is that after the forced …
46.Nxd4
… White has no way of combining queen and knight to attack Black's exposed king. The knight cannot return to e6, and the queenside pawns are firmly blockaded. Meanwhile Black has the bishop-pair and a protected passed pawn, but also cannot make progress. The game should be drawn, which it was (albeit after time-trouble errors).
Updated statistics
Battersea 2018-19
Event...Colour...Grade...Opponent's Grade...Result
CLL........B..........167...….........196...............…D
LL...…….B...…...167...………..159...………….D
CLL...…..B...…...167...………..161...………….W
CLL...…..B...…...167...………..190...………….D
LL...…….W...…..167...………..161...….………W
CLL...…..W...…..167...………..148...………….D
CLL...…..W...…..167...………..165...………….W
CLL...…..W...…..167...………..160...………….D
CLL...…..W...…..167...………..159...………….D
LL...…….B...…...167...………..168...………….D
LL...…….W...…..171...………..159...………….W
CLL...…..B...…...171...………..198...……….….L
CLL...…..B...…...171...………..169...…………..L
CLL...…..B...…...171...………..196...…………..L
LL...…….B...…...171...………..182...…………..D
CLL...…..W...…..171...………..189...…………..L
LL...…….B...…...171...………..178...…………..L
CLL...…..B...…...171...………..164...…………..D
LL...…….B...…...171...………..188...………….W
CLL...…..B...…...171...………..200...…………..L
LL...…….B...…...171...………..169...…………..L
CLL...…..W...…..171...………..186...…………..D
Overall this season for Battersea I have scored +5=10-7 for a grading performance of 171.
In season 2017-18 I scored +10=8-9 for a grading performance of 175.