Kido Taylor-Hart scored a stoppage-time equaliser to secure Arsenal's Division 1 status and leave West Ham United's in peril.
With both sides lying inside the bottom four and playing their final match, Arsenal needed a point to stay above West Ham and clear of the bottom two.
The Gunners trailed 1-0 in the 74th minute, but Nikolaj Moller equalised with a penalty. West Ham regained the lead in the 87th minute, but Taylor-Hart replied at the death.
West Ham are two points above the bottom two and will be relegated if Leicester City win their final match at home against eighth-placed Liverpool on Monday.
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