a/one step behind

A little bit less prepared, skilled, or successful than someone or something else; unable to outmaneuver, outperform, or outpace someone or something. Despite their larger infrastructure and resources, the company's newest high-end PC remains a step behind its competitor's. The cops are always one step behind the notorious criminal. They've been on his trail for 12 years, and they're still no closer to catching him. The fact that we hadn't encountered any of those bugs in our testing put us one step behind when we released the software update.