Answer based on context:

Week 11 saw the Lions trying to win their first game in Pittsburgh since 1955. The Steelers jumped out to an early 14-0 lead, when Ben Roethlisberger hit Antonio Brown with TD passes of 34 and 47 yards on consecutive drives. Detroit got on the board in the second quarter with a 35-yard David Akers field goal, but Pittsburgh went up by 14 again when Shaun Suisham connected on a 25-yard field goal. The Lions made the score 17-10 on the first play of their next possession, when Matthew Stafford found Calvin Johnson for a 79-yard TD pass play. After a 34-yard Suisham field goal, the Lions drew within 3 points when Stafford and Johnson connected again, this time for a 19-yard TD. The Lions took their first lead, 24-20, on a Joique Bell 2-yard run late in the quarter. Detroit had a chance to go up by 11 in the closing seconds of the first half, but after three incomplete passes from the Steelers' 1-yard line, they settled for a 19-yard Akers field goal to make the score 27-20. As the weather turned bad and the field got sloppy in the second half, so did the Lions offense. A 21-yard Suisham field goal was the only score of the third quarter, drawing the Steelers within 4 points at 27-23. The Lions got inside the Pittsburgh 10-yard line on their next possession, but failed to score on three straight plays before calling in the field goal unit. The Lions attempted a fake that failed, and following a Sam Martin fumble, the Steelers took over on their own 3-yard line. Roethlisberger engineered a game-winning 97-yard drive, culminating in a 1-yard TD pass to Will Johnson. The Steelers iced it on their next possession, going up 37-27 after Roethlisberger hit Jerricho Cotchery with a 20-yard TD pass. Matthew Stafford was 19-of-46 passing in the game for 362 yards, including just 3-for-16 in the second half, with many of his passes being dropped by Lions receivers. Ben Roethlisberger, meanwhile, went 29-of-45 for 367 yards and four touchdowns. Calvin Johnson led all players with 179 receiving yards and two touchdowns, but he was shut out in the second half. Despite the loss, Stafford (16,005 yards) passed Bobby Layne's Lion record of 15,710 career passing yards, while Johnson tied Herman Moore's team mark of four consecutive 1,000 yard receiving seasons.

Which player had a fumble, Matthew Stafford or Sam Martin?
a Sam Martin fumble