The Chicago Bears hosted the Buffalo Bills for a joint practice on Friday, where the defense stepped up and left tackles struggled.

We break down Friday's joint practice between the Bears and Bills — how the two starting quarterbacks fared and Mitch Trubisky's return.

Pre-snap penalties remained an issue for the Bears' offensive line, which is still looking for a starting left tackle.

Trubisky spoke with the media on Friday, as the Bills had joint practice with the Bears in Chicago, and was asked what advice he would give to second-year quarterback Caleb Williams - his answer didn't disappoint.

Curtis Samuel's job appears at risk, even after he returned to practice, and Mitch Trubisky expanded his lead over Mike White.

The Buffalo Bills saw their 30-year-old free-agent addition wreak havoc in Friday's joint practice, on the road, against the Chicago Bears

Unlike the first preseason game, the Bears are set to play the starters this weekend against the Bills, including quarterback Caleb Williams, so that the offense can get a taste of live game situations. So, let's breakdown the Top-5 things to watch for on Sunday night.

The Chicago Bears were back at Halas Hall for their 17th practice of training camp, where there were plenty of notable observations and highlights from Thursday's session.