Table:
text: Mikhail Ilyukhin
Mixed martial arts record
Mixed martial arts record
Res_ Record Opponent Method_ Round Location_
Win 10-0 Achmed Sagidgusenov Submission (achilles lock) 1 Moscow , Russia
Win 9-0 Igor Vovchanchyn Submission (chin in the eye) 1 Moscow , Russia
Win 8-0 Andrei Besedin Submission (guillotine choke) 1 Moscow , Russia
Win 7-0 Zagil Eribinov Submission (armbar) 1 Moscow , Russia
Win 6-0 Nikolai Zouev Submission 1 Fukuoka, Japan
Win 5-0 Victor Yerohin Submission (rear naked choke) 1 Moscow , Russia
Win 4-0 Leonid Efremov Submission (achilles lock) 1 Moscow , Russia
Win 3-0 Vadim Shevchenko Submission (achilles lock) 1 Moscow , Russia
Win 2-0 Maxim Tarasov Submission (achilles lock) 1 Moscow , Russia
Win 1-0 Piotr Tjernov Submission (achilles lock) 1 Moscow , Russia

Question: What was the solution method when Mikhail Ilyukhin was 4-0 among USSR players at the World Cup?