They've been part of each other's lives since 2004.
Their names are etched together atop the record books, forever paired in football immortality.
Now, after 14 historic, memorable seasons together, Philip Rivers offered a heartfelt goodbye to Antonio Gates on Monday as he reflected on their time together.
"The first thing that pops in your head is he owns so many tight end records," Rivers said. "But to me, he'll always be one of my all-time favorite teammates. Our friendship we developed over the years from the time spent and the trust built. From the tough games, the awesome wins and all the experiences we had together. It was a unique opportunity to play with a guy like that."
In true Rivers fashion, his voice trembled with emotion and his pace picked up as he talked about all things Gates.
"It was those games when he had ribs that were hurt, a dislocated big toe and all that stuff, but you just knew he would be out there. It shows the competitor he was. There's nothing left for him to prove. He did it all. He was a championship player. On the outside, people will remember him for the catches and yards, but he was so much more than that to me. Just the day-to-day interactions that we had, and the fun we had, I couldn't be more thankful."
It's nearly impossible to discuss Rivers' career without mentioning Gates….and number 17 is adamant that he wouldn't be where he is today without the legendary tight end.
Just look at all their accomplishments.
Eighty-seven times the pair connected for a touchdown, which is the most all-time by a quarterback-tight end duo.
In fact, their 87 TDs are the second-most by any duo in NFL history, trailing only Peyton Manning-to-Marvin Harrison (112). The pair passed Steve Young-to-Jerry Rice (85) last year for sole possession of second place.
"That is special," Rivers stressed. "Speaking from a selfish standpoint, I don't know where I'd be without him. If he hadn't been here for 14 years, I don't know what my career is like. You're talking about a pretty unique opportunity to be paired with the best tight end who has more touchdowns than anybody. And then I'm able to share in many of them. It's awesome, and that part is important. It's great to have something we can share together. That part is cool and special to both of us. When you see the names like Young and Rice, Peyton and Marvin, and you see Rivers and Gates; that is special."
The two spent so much time together that they forged a bond unique from any other.
"I'll miss him, that's for sure. I'll miss those special moments that I can't really describe. It's on the field, those conversations where I'll give him just a pat here or there, but really, it's just the day-to-day. We were next to each other for years. That's what I'll really miss the most. We had a long time together. The things we would laugh about and share, we would think the same things so many times. Somebody would say something, and only he and I would look at each other and it would be, 'You didn't just think that, too!' But because we spent so much time together, we thought about so many things the same."
Rivers knows football better than pretty much anyone. Yet it doesn't take a savant to know that what Gates did in the passing game simply redefined the tight end position forever.
"On the outside looking in, you're going to think of the pivot route and corner route, and know he was the best at both of them. Not that he couldn't run many, many other routes. But those two when it comes to mind, it was just, put him at on a seven, let him run a pivot and they've got no chance."
Then there's what the team called the Gates Rule.
"For so long we had what we called the Gates Rule which was, here's the play, here's the read, *but, *remember the Gates Rule," Rivers explained. "It was that he can probably beat anybody, so if you think he's going to win, you can work it there. The Gates Rule trumped the whole white board."
So, what does Rivers consider to be Gates' legacy?
"Obviously one of the greatest Chargers of all time regardless of position. You're talking about the best tight end ever. Obviously, he has the most touchdowns of any tight end, and holds every receiving category in this organization. But he was more than that. The competitor he is was second to none. He competed in everything. If we're just sitting here arguing about a player, he's going to win the argument every time. He was just going to compete in everything. But really, when you think of him, he's obviously one of the greatest Chargers."
Check out the top 85 photos from the first 15 seasons of Gates' career.