Editing Perpetual check (section)

===Unzicker vs. Averbakh===
{{Chess diagram
|tright
|Unzicker vs. Averbakh, 1952
|  |  |  |  |  |rd|kd|  
|  |rd|pl|  |  |  |pd|pd
|pd|  |  |  |  |nd|  |  
|  |  |  |pl|pd|  |  |  
|  |pl|  |  |pl|qd|  |  
|  |  |ql|  |  |  |  |pl
|pl|  |  |  |  |  |pl|  
|rl|  |  |  |rl|  |kl|  
|Perpetual check extricates Black from his difficulties.
}}
In the diagram, from [[Wolfgang Unzicker]]–[[Yuri Averbakh]], Stockholm [[Interzonal]] 1952,<ref>{{cite web |url=http://www.chessgames.com/perl/chessgame?gid=1153024 |title=Unzicker vs. Averbakh, Stockholm 1952 |website=[[Chessgames.com]] }}</ref> Black (on move) would soon be forced to give up one of his [[rook (chess)|rooks]] for White's c-[[pawn (chess)|pawn]] (to prevent it from [[promotion (chess)|promoting]] or to capture the promoted [[queen (chess)|queen]] after promotion). He can, however, exploit the weakness of White's {{chessgloss|kingside}} [[pawn structure]] with 
:'''27... Rxc7{{chesspunc|!}}'''
:'''28. Qxc7 Ng4!''' 
Threatening 29...Qh2{{chessAN|#}}. If 29.hxg4 then 29...Qf2+, salvaging a draw by threefold repetition with checks by moving the queen alternatively to f2 and h4.
{{clear}}