NFL coach Robert Saleh exposes rival team's sign stealing before their Sunday showdown

49ers defensive coordinator Robert Saleh has exposed the Jaguars' 'really advanced' sign-stealing scheme ahead of their matchup in San Francisco this weekend.

While sign-stealing has previously led to the Houston Astros and University of Michigan football team being punished, Saleh pointed out that what Jacksonville and head coach Liam Coen are apparently doing is legal. 

'Liam and his staff, couple guys coming from Minnesota, they've got a - legally - really advanced signal-stealing type system where they always find a way to put themselves in an advantageous situation,' Saleh told reporters.

'They do a great job of it. They formation you to just try to find any nugget they can. So we've got to be great with our signals and we've gotta be great with our communication to combat some of the tells that we might give on the field.'

Saleh, who re-joined the 49ers following his ouster as Jets head coach last year (and a short stint as a Packers offensive consultant), added that sign-stealing is a particular skill of the Sean McVay coaching tree.

Coen was previously McVay's offensive coordinator on the Rams, and so too was Vikings coach Kevin O'Connell - who Jacksonville OC Grant Udinski previously worked under in Minnesota.

'They're almost elite in that regard. That whole entire tree from Sean to Kevin O'Connell to all of those guys, they all do it,' Saleh continued. 

'There's challenges. They're going to catch us in some situations where they have the advantage and we've just got to play sound, fundamental football and do our best to out-execute them.'

Saleh went on to call sign-stealing the 'ultimate trick' before explaining how Coen and Co. could gain an upper hand. 

'Whether it's people from the sideline or whether it's our individual hand signals -whatever nugget they can find, they catch it. And they always happen to find themselves in good situations based on the coverages shown,' he said. 

'And there's nothing illegal about it. I'm not suggesting that. It's just, you can tell they have a system that is getting them into a very advantageous position multiple times during the course of a game.'

Through three games, Saleh's defense has allowed the second-least points in the league at 16.3 per contest.

Jacksonville, meanwhile, has had a middle-of-the-pack scoring offense, as its 23.3 points per game are tied for 14th in the league.

Those units will face off when the 49ers (3-0) host the Jaguars (2-1) at 4:05ET on Sunday.