Even though we are only four weeks into the NFL season, certain players have displayed unquestionable talent thus far. While their fantasy owners may be unlikely to trade them now, they are still worthy trade targets as their stock may not be done rising.

Philip Rivers (QB, Chargers): Rivers was often overlooked in the preseason in favor of flashier players like Cam Newton (Panthers) or Colin Kaepernick (49ers). However, there may not be anyone playing as well as Rivers right now. While that doesn't necessarily make Rivers an elite fantasy option, he still is a clear-cut top seven fantasy QB.

Le'Veon Bell (RB, Steelers): Bell seems like a new man this year, one of the rare backs who can kill defenses between the tackles or in the passing game. After a sea of negative preseason buzz, few saw this coming. And if you were to redraft your team today, it wouldn't be crazy to make Bell a top three pick.

Jordy Nelson (WR, Packers): Nelson seemed like one of those solid, dependable WRs who consistently produces but rarely explodes. But as of this year he seems to have developed a telekinetic connection with QB Aaron Rodgers that has made him nearly unstoppable. While Nelson was already considered a low-end WR1 in the preseason, he can now be placed alongside the likes of A.J. Green (Bengals) and Dez Bryant (Cowboys) in the sub-Calvin Johnson tier of fantasy WRs.

Martellus Bennett (TE, Bears): It was difficult to be too enthusiastic about Bennett in the preseason, as it seemed unlikely there would be enough TD scraps left behind after Bears WRs Brandon Marshall and Alshon Jeffery were fed. However, Bennett has proved their equal this year and should be considered a borderline top five TE moving forward.

Alex Case is amNY's fantasy football columnist.