On the Bears' first possession of the second half Sunday night, the offense faced third-and-nine at its own 22 while trailing Green Bay 24-7.

With Justin Fields in shotgun formation, Equanimeous St. Brown lined up outside to run a curl route. But once St. Brown made a quick inside cut, the receiver said he "beat the DB so bad," that he turned it into a go route, ending up wide open down the right side of the field.

While St. Brown threw his hand up at the Bears' 35 with open field in front of him, Fields opted for a 7-yard check down pass to David Montgomery, bringing up fourth-and-2.

"When we throw a hand up, we call it "mailbox,'" St. Brown said. "So if you're not gonna run your route and you're gonna run the go route, throw your hand up so the quarterback knows you're gonna run a go route and not the actual route you were gonna run."

Coach Matt Eberflus said St. Brown converted his route on that play and Fields "just didn't see him at that moment."

That type of situation is one St. Brown believes will improve as he and Fields gain more experience together. While the pair have discussed the mailbox signal, St. Brown said this was the first time it occurred in live action. 

"I think that might've been the first situation we've had all camp, OTAs, where that happened," St. Brown said. "We talked about that. But I think that's the first time that happened in an actual situation, practice or game. So I think moving forward, things like that we'll connect on."

Fields and St. Brown did connect on a 30-yard flea flicker on the Bears' opening drive of the game. The completion pushed the offense into Packers' territory at the 25. Three plays later, Fields scored a 3-yard rushing touchdown to give the Bears a 7-3 lead. 

While receiver Darnell Mooney was Fields' first read on that play, St. Brown said he was "definitely a viable option."

"We've run that play multiple times in practice," Fields said after the game. "Saw one high [safety], couldn't see Mooney. He's the first read on that, but I couldn't see him, so I just went outside to EQ. And EQ had a good run after the catch, a good look."

Through two games, St. Brown has been targeted a team-high 7 times, catching three passes, and has the most receiving yards with 57. 

While no one is content with the results of the passing game, St. Brown said the team is still working on fine tuning the details of a new scheme. 

"I think that every team that has a new offense, it's going to take some time to get all the little details correct," St. Brown said. "It's not easy to do it on a consistent basis. The defense gets paid to stop you as well. So, I think any time a team has a new coach, new offense, it's going to take some time to get a grip on it."

The receiver does anticipate the passing game being more explosive in the future, expressing confidence in the group's talent. 

"I think we have a lot of good playmakers in our receiver room," St. Brown said. "We have a great quarterback. It's only our second game with this new system, and I think as we go into the season, we'll heat up more."