Even when an arbitration agreement contains a broad delegation clause, the court must first determine whether the parties entered into the arbitration agreement. Plaintiff who challenges the authenticity of his signature on the arbitration agreement needn’t prove it is not authentic but must submit sufficient facts to create a disputed issue of fact, thus shifting the burden back to the defendant. Simply denying that plaintiff signed the agreement suffices. Here, the employer could not thereafter prove the signature was authentic. Its evidence didn’t show that only plaintiff could have place her electronic signature on the arbitration agreement.