The bout has been targeted to serve as the co-main event. UFC 229 stands to be one of the biggest events in the company's history, as it will be headlined by a lightweight title fight between Khabib Nurmagomedov and Conor McGregor.
Lewis (20-5) is coming off a widely criticized decision win against Francis Ngannou at UFC 226 last month. According to Fightmetric, the two combined for just 31 total strikes in that 15-minute contest.
Lewis, of Houston, apologized for his performance immediately after. He also admitted to suffering from a back injury prior to the bout.
Volkov (30-6), of Moscow, is riding a six-fight win streak. He scored a fourth-round knockout over former champion Fabricio Werdum five months ago at a UFC Fight Night event.
ESPN ranks Volkov and Lewis the Nos. 3 and 5 heavyweights in the world, respectively.