Slay expected the first rep. He knew Brown would want to show off for the fans and he was cool with it. Then the second rep went deep. Then the third. And Slay looked at him.
"It's like, 'Come on, we're going to run another deep route,'" Slay said. "He said, 'I'm gonna go deep all day, Slay.'"
At least in individuals he did and after the third rep, Slay looked to his left and saw an official with them. So he started to chat with him as Brown trailed behind the two of them. It was a friendly competition between the star Pittsburgh Steelers receiver and the emerging Lions corner, but Slay wanted the official to know something.
"Telling him to stop pushing me off the top of the route, man," Slay said. "I mean, I feel the arm in the back and I said, 'Oh Lord,' I'm not trying to bust my behind out here.' But we getting that work in, though, man. But I love it.
"I love the game he got. He's a very, very competitive guy, man. Like I said, he's one of the best in the business right now so he's showing it right now, too."
On Tuesday he showed it against Slay, and while the corner is exceedingly competitive, he also realized reps against Brown will make him better. In previous years in practice, he often matched up against the tall, truck-like figure that was Calvin Johnson. He learned how to play tall receivers then.
Brown is not that. Brown is 5-foot-10, but he has the shiftiness and quickness off the line of scrimmage to force defenders to have to adjust -- and typically fail -- on the fly. Slay said he didn't want to mess with Brown at the line of scrimmage because he is that difficult to deal with and can cause a corner to look real bad really fast.
"He presents a very, very unusual challenge for him," Lions coach Jim Caldwell said. "Because he's a guy that's fast. He's quick. He's an extremely smart guy just in terms of understanding how he disrupts the coverage techniques of defenders."
Slay noticed that immediately. He said he hasn't faced anyone like Brown in the NFC North. The division either had bigger guys like Alshon Jeffery and Brandon Marshall with Chicago, Jordy Nelson in Green Bay and Slay's old teammate, Johnson. Then there were the straight speed guys like Mike Wallace, who played for Minnesota last season.
So this can only help him, especially as he becomes the corner likely to face an opponent's top receiver every week no matter size or speed.
And Slay hung with Brown for the most part. Other than the first rep in one-on-one work where Brown breezed by him, Slay was in good position both times. Brown just had better positioning, even though he dropped one of the three deep balls. In team drills, Slay hung with Brown well.
He doesn't mind Brown's chatter, either. He compared his talk to what Lions receiver Golden Tate does on a daily basis, even calling him "the GT of Pittsburgh." And Slay is cool with it, especially if he can stop him.
Slay took it as "a big challenge" and there were things he took from it, even from one day in practice.
"I got to play the deep ball better so I won't be able to get pushed off," Slay said. "I'll just finish the route, you know, because I guess when I look back, that's the indicator for him to get his separation.
"So I think I just need to finish through the ball."
But Slay understands the challenge. He knows he'll possibly get two more shots at Brown. He'll face him again in practice Wednesday. He might see him one final time in the preseason opener Friday at Heinz Field. He understands what he has to do.
He said he has a better feel for Brown now -- both how he plays and possibly how Slay can stop him. If he does, that could help Slay learn even more.
"It's a big measuring stick," Slay said. "It's just a different type of guy and just gonna make the plays. I just gotta make more plays.
"I made a couple today. I just need to make more."