Elegant Square Clearing Pawn Move

 Austrian Chess player Arsenal11 must have thought he stood no worse after the solid looking g6 pawn move. After all, his King on e6 had the opposition over its White counterpart on the e4 square.

However, he overlooked the game winning space clearance move pawn to f5 EXCLAM. So what space was cleared from this temporary pawn sacrifice? The f4 square, to be occupied by White Monarch, is the answer when Black finds himself in Zugzwang( German for NO move I think) 

Not only will Black's f5 fall, but the c5 pawn could be lost in some variations. Also if Black moves his pawn f6, White's g pawn jettisons Bruce Pandolfini! 

BTW, I have heard soccer goalkeeper Aaron Ramsdale has more than a mild interest in the Royal Game

Eloping Female Chess Player Reference

 The made for movies drama involving an American International Master and a Russian female who was using him to get to the USA popped into my mind after this sacrifice the farm game of chess played at the Internet Chess Club. The Russian female later divorced IM Donaldson and married another edgy, easy to irritate  chess player named Orlov who loves to move his Horses before his pawns in the opening. The dude also loved to Tango!!  

Black is already down a piece in the diagrammed position and it is not really clear who is attacking whom in a position where many commentators would just bale with  "chances for both sides". However there is a concrete continuation based on the violent tactical theme of diagonal clearance. The Nd4 is a forcing continuation due to the fork of the Queen and King and the move also threatens the eviscerating Ba4 CHECK!

John wrote some nice annotations where he suffered through a sacrifice the house attack at the hands of the Lexington Lion GM Gregory Kaidanov.  The former employee of Yasser Seirawan also wrote a nice opening tome on the Meran Defense. IM Donaldson is  a good teacher also. 

Back Rank Clearance Tactical Motif

Not sure if back rank clearance is common parlance, but perhaps a glance at the diagrammed position will define it by picture. 

It is well known that hanging (en prise pieces) are the origin of any tactical sequence. Combine that with King safety and it is not difficult to see why Bishop to the g4 square initiates the fireworks against knightjouster5 during a blitz game at the internet chess club. BTW GM Jesse Kraai believes online chess along with the COVID-19 might irreversibly damage the long time control aspect of our beloved Royal Game. He and Greg Shahade are extreme adversaries in the short versus long time control paradigm shift!! Kraai's pithy and incisive column in Chess Life should win multiple awards!

Back to the diagram. White's hanging Queen at c2 and rook at a1 fully justify the "hanging attack" Bg4. Work through the variations. IT IS STUNNING!!

I am certain Saint Louis chess club commentator Jonathan Schrantz would include this in one of his instructional videos.