"We had to win this game," Romo said.
Romo originally was hurt two weeks ago, fracturing two small bones in his back. He started in London to help the Cowboys (7-3) snap a two-game losing streak.
Romo completed 20 of 27 passes for 246 yards against the Jaguars (1-9) and finished with a season-high passer rating of 138.8.
The game was played at Wembley Stadium, the home of England's national soccer team. It was the last of three regular-season NFL games this year in the British capital.
The Cowboys have played outside the United States 10 times, but this was the first game that actually affected their record. With Dallas comfortably ahead, Romo sat out the final 6:42.
"Just sore. Anybody who's had anything broken before knows it's uncomfortable at times," Romo said. "A little banged up. A lot of guys are banged up. At the end of the day, no one actually cares once you step out onto the field."
Bryant gained all of his 158 yards in the second quarter, and did it by breaking several tackles on each touchdown catch.
"We kind of shot ourselves in the foot for two or three drives after that (first touchdown) and never really got it rolling again," Bortles said.
Soon after, everything changed.
Murray ran for 4 yards on the first play. After a pass to Bryant was broken up, Romo found Witten in the end zone.
"That was the play early on that really swung the tide," Garrett said of the fumble. "We played pretty solid football after that."
From the start on Sunday, Romo looked good but didn't seem 100 percent. He overthrew a wide open Witten on third down on the first series, and then threw the short pass to Witten for the first touchdown when he likely would have run it himself without the injury.
Romo, who has thrown at least one TD pass in an NFL-record 37 consecutive road games, was also well protected by the offensive line, despite the Jaguars having one of the top pass rushes in the league.
"He missed one early to Witten, a touchdown opportunity for us," Garrett said of Romo. "But really besides that I thought he played a really good ball game, really looked like he saw the field well."
Weeden, who is 0-1 as a starting quarterback for the Cowboys after last week's loss, came on for Romo in the final minutes and played until the end as the fans emptied the stadium early.
NOTES: Romo is now 25-5 in November, by far the best of any of his months. ... The players on both teams wore poppies on their shirts and helmets to commemorate Remembrance Day in Britain, the equivalent of Memorial Day in the United States. The little red flower is worn by many British people every year to honor Britain's war dead in the days leading up to Nov. 11, the day in 1918 when hostilities ceased at the end of World War I. ... The NFL will play three more regular-season games at Wembley Stadium next year. The Jaguars, who are now halfway through a four-year deal to play in London, will face the Buffalo Bills on Oct. 25, while the Miami Dolphins play the New York Jets on Oct. 4 and the Kansas City Chiefs meet the Detroit Lions on Nov. 1.
Copyright 2014 by The Associated Press