What to watch in Week 6 of the NFL: A Harbaugh in trouble, problems in the City of Angels and a London showdown

Five weeks into the NFL season, three teams remain unbeaten, a Super Bowl favorite is suddenly struggling and one high-profile head coach is already feeling the heat. With division rivalries, a Sunday night shootout and a crucial London showdown on tap, Week 6 could tell us a lot about which teams are legitimate contenders and which are headed for disappointment. Here’s what to know ahead of this week’s NFL action. The Undefeateds We’re down to just three undefeated teams, and none has been more impressive than the San Francisco 49ers. Kyle Shanahan has his team off to a 5-0 start for the third time in seven years, and the wins couldn’t be much more impressive. The 49ers have already beaten three of last season’s conference finalists: the Denver Broncos, Seattle Seahawks and Los Angeles Rams.