be a/one step behind

To be consistently outperformed, outmaneuvered, or evaded (by someone or something). That cops are always a step behind the notorious criminal. They've been on his trail for 12 years, and they're still no closer to catching him. Despite their larger infrastructure and resources, the company's newest high-end PC is still one step behind its competitor's. Because we hadn't encountered any of those bugs in our testing, we were one step behind when we released the software update.