Allen Park — San Francisco 49ers coach Kyle Shanahan doesn’t have a lot to go on when studying for this weekend’s matchup with the Detroit Lions. As far as he's concerned, he doesn’t even have a full game.

“It’s always tough when you play a team that doesn’t have much tape,” Shanahan said during a Wednesday conference call with reporters. “You can go through the preseason, where everyone’s pretty vanilla in the preseason, or we can watch the game that we had on Monday night, but that was only about two and a half quarters until it was four-minute drill. So, there’s not a lot of tape on Detroit’s defense right now."

It’s a valid point.

After the New York Jets got up 31 points on the Lions in the third quarter on Monday night, there was not much to be gleaned from the rest of the night.

More: Lions film review: Five observations vs. Jets

More: Matt Patricia refocuses Lions: 'We're going to move on'

But instead of relying on guesswork to fill the voids of understanding, Shanahan’s staff is doing the next best thing to having more Lions film to study. They’re going back to watching old New England Patriots tape, where Patricia served as defensive coordinator the past six years.

That tape includes Super Bowl LI, when Shanahan was serving as offensive coordinator of the Atlanta Falcons against Patricia’s Patriots.

“Yeah, I already have (watched that),” Shanahan said. “I’ve been watching a lot of stuff. Not just over the last couple days but over the summer and things like that. We’re always watching film and you love to watch the players that we’re going against.”

That game probably doesn’t bring back fond memories for Shanahan, after his team blew a 28-3 lead in the second half. But prior to the comeback, the Falcons' offense was having plenty of success against Patricia’s defense.

“We stayed ahead of the chains, we didn’t have too many third downs, we ran the ball and had some good explosives (plays) off of it, and we made some big plays down the field in the pass game,” Shanahan said. “Second half it was just tough to get out there. We didn’t convert any third downs, we never stayed on the field, we had 20 plays in the second half. So, it never felt like we really got to play football there in the second half.”

Both the Lions and 49ers will be looking to avoid 0-2 starts to the season. The 49ers lost, 24-16, to the Minnesota Vikings last week.

Lions at 49ers

Kickoff: 4:05 p.m. Sunday, Levi’s Stadium, San Francisco

TV/radio: Fox/760

Records: Both teams are 0-1

Line: 49ers by 6