London - For the St. Louis Rams' much-improved defense, this overseas trip will be anything but a holiday.

The Rams' defense had been one of the biggest surprises in the NFL this season until given a reality check at home last weekend by Aaron Rodgers and the Green Bay Packers. Things aren't about to get easier this weekend.

The Rams (3-4) host Tom Brady and the New England Patriots (4-3) today at Wembley Stadium in the annual NFL game in London, offering another chance to prove they can stand up to the best offenses in the league.

"It's a huge challenge. Back-to-back weeks we go from league MVP to Super Bowl MVP, and you name it," Rams cornerback Cortland Finnegan said. "You look forward to those kinds of things. It's a great challenge for us as a secondary and as a defense."

Before losing 30-20 to the Packers, the Rams had limited opponents to 14.7 points per game at home in the Edward Jones Dome in victories over the Redskins, Seahawks and Cardinals. Despite a young roster, they have the 10th-ranked defense in the league overall after being 22nd last year.

Give coach Jeff Fisher credit, said Patriots counterpart Bill Belichick, who has been impressed with the Rams' turnaround after going 2-14 last year.

"Jeff as usual has done a great coaching job there," Belichick said. "It looks like they're very sound. They do things well fundamentally and you really have to do a good job against them. ... He's molded it into a real competitive football team in a hurry."

Fisher, however, was quick to point out that two of the team's wins came against rookie quarterbacks. So there's still a need for rapid improvements to have a chance against Brady and New England's top-ranked offense.

"They're playing as a group probably as good as they've ever played, in my opinion," Fisher said about the Patriots. "With the weapons that he (Brady) has now, the healthy tight ends, the versatile backs that he has out in the backfield, and of course the receiving corps. ... It puts a lot of pressure on the defense. We're going to have to obviously slow that pace down a little bit."

The Rams and Patriots have taken different approaches to preparing for the game. The Rams arrived Tuesday to get acclimated to the time difference and surroundings, while the Patriots headed over on Friday.

New England has been here before, however, beating Tampa Bay at Wembley in 2009.

For the NFL, the London games are about growing the popularity of the sport outside the United States - a plan that has worked well in the previous five years a regular-season game has been held here. The league has reported steadily increasing TV ratings and fan interest in Europe since 2007, and will play two games at Wembley next year.

While the Patriots and Rams are both buying into that idea, they're careful not to let it become a distraction.

"We're focused in on the Rams," Brady said. "I know (the league) put a lot of effort into it and I know (owner Robert) Kraft is excited about us really having a chance to represent the NFL again and go over there and give the fans something to cheer about. It was a lot of fun the last time."

The Rams can't count on much of a home-field advantage either, despite being listed as the "home" team. The Patriots certainly are by far the better-known team in Europe, and Brady's star power and three Super Bowl titles has already helped the team build a solid fan base overseas.

While the Wembley games traditionally have fans cheering for both teams - and wearing the jerseys of every franchise in the league - the Patriots are expected to get a majority of the support.

"Whoever shows up to support American football, we'll gladly welcome them," Fisher said.