Bears LB Brian Urlacher celebrates his 85-yard interception return for a touchdown in last year's Packers-Bears game at Soldier Field in Chicago.

As Head Coach Mike McCarthy has discussed several times, the Packers have a "ball security" period during every practice, when offensive players work on drills to protect the football and defensive players focus on taking it away.

That practice period may carry no higher importance than it does this week with the Chicago Bears coming to town.

While turnovers are often a key barometer in the win-loss equation, they seem to be the deciding factor almost without fail against the Bears, a defense that prides itself on turnovers - no matter where they're ranked in other defensive categories - and that's tied for the league lead in takeaways once again this season with 20.

"That's something we harp on quite a bit," Bears head coach Lovie Smith said. "We put an emphasis on it. Our defensive guys do a great job of trying to get the ball away. It's about doing whatever you can to either score points or get the ball back for your offense as soon as you can."

While Smith has followed through on his stated No. 1 goal of beating the Packers, having gone 6-2 against Green Bay since getting the Chicago job in 2004, he's done it with that emphasis on takeaways. In fact, the Packers have outgained the Bears in total yards five of the six times they've lost to Chicago under Smith, and here's a brief look at the role turnovers played in those six losses:

--Sept. 19, 2004: Bears 21, Packers 10

With the Packers poised to score and take a 10-7 halftime lead, linebacker Brian Urlacher stripped running back Ahman Green of the ball at the Chicago 2-yard line, and safety Mike Brown returned the fumble 95 yards for a touchdown, the most costly of Green Bay's three turnovers.

--Dec. 4, 2005: Bears 19, Packers 7

The Packers nearly doubled the Bears' yardage output (358-190), but the Packers fumbled four times, losing two. The Bears also had two interceptions, one returned 95 yards by cornerback Charles Tillman to set up a field goal just before halftime, and another returned 45 yards by cornerback Nathan Vasher for a touchdown in the second half.

--Dec. 25, 2005: Bears 24, Packers 17

The Bears record four interceptions, including one returned 10 yards for a score by linebacker Lance Briggs.

--Sept. 10, 2006: Bears 26, Packers 0

This was the one game the Bears actually outgained the Packers, but two interceptions and a fumble still played a role in McCarthy's forgettable regular-season debut.

--Oct. 7, 2007: Bears 27, Packers 20

In the first half alone, the Packers rolled up 341 total yards and 15 first downs, yet led only 17-7 because Tillman stripped receiver James Jones of the ball twice after receptions over the middle. "We had as productive a half offensively as we've had in a long time, but turnovers," McCarthy said. "It all goes back to fundamentals." The Packers finished with 439 yards of offense (to Chicago's 285), but three lost fumbles in all and an interception by Urlacher in the third quarter spurred the Bears' come-from-behind win.

--Dec. 23, 2007: Bears 35, Packers 7

The Packers had all kinds of ball security issues in the bitterly cold and windy conditions. Four fumbles were all recovered by Green Bay, but two blocked punts and two interceptions, one returned for a score by Urlacher, turned this into a runaway.

On the flip side, McCarthy's one win against Chicago, in the 2006 regular-season finale, was also turnover-driven. The Packers returned two interceptions for touchdowns and had six takeaways in all in a 26-7 victory. And when the Packers beat the Bears in the 2004 regular-season finale, Green Bay did not have a turnover.

{sportsad300}How the Packers do in the takeaway department on Sunday could be dependent on Chicago's quarterback. If Kyle Orton returns from his ankle injury, the Bears might protect the ball better than if Rex Grossman has to start in Orton's place again. Orton threw just four interceptions in the first 7 1/2 games this season, while Grossman has thrown two picks in his 1 1/2 games in relief. Orton has lost three of four fumbles this season, however.

"He does a good job of managing the game, taking care of the ball," linebacker A.J. Hawk said of Orton, a former Purdue quarterback Hawk faced while playing at Ohio State. "That's what I think a lot of head coaches and coordinators, they preach that first, take care of the ball. He does a good job of that as well as taking some shots and making some plays."

Added Urlacher: "He's taken sacks but not turned the ball over in bad spots. We have turned the ball over, but not where it hurts our defense or our team."

The Packers, meanwhile, have just 10 giveaways on the season, four fewer than the Bears. Quarterback Aaron Rodgers has thrown only five interceptions in nine starts, and three of those came in one game (at Tampa Bay, Week 4). Like Orton, he also has three lost fumbles. Running back Ryan Grant has lost two fumbles for the Packers, but none in the last five contests.

The Packers haven't played a turnover-free game against the Bears since that 2004 regular-season finale. Repeat that feat and Green Bay's four-game losing streak to Chicago at Lambeau Field could very well be history.

"I think we've won four in a row up there, I'm sure they know that, so it's going to be an emphasis for them this week," Urlacher said. "It's a big deal to us."