Force as many turnovers as possible to prepare for more of the same come Sunday. Linebacker NaVorro Bowman claims his unit had nine turnovers during one such session recently – though quarterback Alex Smith begs to differ, calling that number inflated.
The total hardly matters, it's the principle.
''We go out and try to make as few mistakes as we possibly can,'' Bowman said. ''We work on it every single day. We see where we end up and go into the game with that type of mindset.''
49ers coach Jim Harbaugh isn't keeping track of turnovers in practice, though he loves the intense competition by his players leading up to games – and he's certainly thrilled that his defense delivered once again with an interception and forced the New York Jets into three lost fumbles in Sunday's 34-0 win at the Meadowlands.
''It's the practice of the fundamentals of recovering footballs, diving on mistakes, clubbing, ripping, jarring the ball loose,'' Harbaugh said Monday of what goes into the preparation. ''They treat each other with a great amount of respect, which I've always admired about our team. They enjoy the competition. It's competitive but not self-centered.''
The dominant performance by defensive coordinator Vic Fangio's crew kept the Jets out of the red zone all day, and further established the 49ers (3-1) as one of the NFL's elite teams even after that blip at Minnesota in a 24-13 Week 3 loss.
Harbaugh said the 49ers had prepared for Tim Tebow's signature jump pass even though New York had yet to run it, so San Francisco had no film of the play. In New York's first drive of the second quarter, Tebow completed a 9-yard pass to Dedrick Epps, who wound up fumbling as safety Dashon Goldson forced it and recovered.
It was the first turnover of three in a four-series stretch by the Jets.
The Buffalo Bills will try to clean things up in a hurry to avoid another ugly loss Sunday when they visit Candlestick Park. They committed six turnovers and blew a 14-point third-quarter lead in losing 52-28 at home to Tom Brady and the New England Patriots on Sunday.
Harbaugh's defense will be ready to pounce on any error.
''That was a gem our defense turned in,'' Harbaugh said, back in the Bay Area for the first time in 10 days after practicing in eastern Ohio ahead of last week's game. ''Every guy played within the framework of the defense, playing their ace they had individually.''
Jets quarterback Mark Sanchez threw an interception and lost a fumble. He was sacked by Aldon Smith late in the first half and fumbled, with Justin Smith recovering.
That play gave the 49ers another chance before halftime, and David Akers kicked a 36-yard field goal to make it 10-0.
New York's longest drive was 30 yards – to open the game – and it ended in a punt. The Jets had seven drives that gained eight yards or fewer and they never picked up more than two first downs on any drive. Six New York possessions ended without a first down and three others gained just one first down.
''Defensively, we knew how we came and played last week,'' cornerback Carlos Rogers said. ''Coach Vic talked this week and told us to play 49ers ball and play how we should play. Did we imagine a shutout? No, but we finished plays, got turnovers, and got off the field on third down. We got some gifts on defense and we got in the end zone.''
Rogers, who shared the team lead with six interceptions last season, recovered a fumble by Santonio Holmes after the receiver's short catch on the first play of the fourth quarter and returned it 51 yards for a touchdown. Holmes injured his foot on the play.
Rogers also recovered another fumble. He scored his first career touchdown off a fumble recovery and third ever.
The 49ers made keeping their defense together a top priority during the offseason. All 11 starters from last season's 13-3 team returned, though linebacker Parys Haralson was lost for the season early last month with a torn left triceps muscle.
The Niners had 38 takeaways during the 2011 regular season to only 10 turnovers. Their plus-28 turnover differential matched the 2010 Patriots for the second-best mark in NFL history since 1941.
This opportunistic defense prides itself on wreaking havoc from every direction, from so many positions and faces. That keeps any offense guessing with so many defenders who can change the momentum just like that.
San Francisco managed its first shutout on the road since Jan. 6, 2002, at New Orleans, limiting the Jets to just 145 total net yards of offense – the Niners' lowest total net yards allowed since giving up only 109 on Jan. 3, 2010, at St. Louis.
''We were able to get pressure on (Sanchez), make his throws hard, and get sacks. I think we did a good job,'' said Aldon Smith, whose 14 sacks last season were a 49ers rookie record. ''After the last game, some people questioned us. We know what we are capable of. We are a good defense that plays well together.''
And also takes the ball away from others well together.