Floyd went for the dap.

The result was ... well, it was a mess.

Once again, Floyd Mayweather and Manny Pacquiao came face-to-face at the Lakers game -- in what seems to be more shameless promotion for an upcoming rematch.

Floyd was sitting on the court at Staples Center in L.A. to watch the Lakers take on the Warriors (they lost) ... when Manny came up from behind to say "What's up."

The handshake greeting was a disaster -- but they got the point across.

The big problem ... Manny reportedly suffered an eye injury during his victory over Adrien Broner this past weekend -- which could throw a huge wrench in the rematch plans.

According to reports, Manny feared he suffered a detached retina in his left eye. Later, his manager said the eye was "fine" and he'll be okay.

Manny was wearing shades at the game -- so you can't see if the eye looks damaged on the surface.

As we previously reported, Manny and Floyd have been teasing a rematch for months ... and with both fighters looking pretty solid in their last fights, it seems a deal could be close.

The two originally fought back in 2015 -- with Floyd winning a unanimous decision in a pretty boring fight.

We recently spoke with Manny who told us he had a bad shoulder at the time -- and now that he's fully healed, he's confident he would whoop that ass.

No deal has been made at this point -- but we're guessing it's just a matter of time ... considering the money these guys could rake in.

There were other big stars at the Lakers game too -- including Halsey, Alexis Ren, Mahershala Ali, Jack Nicholson and LeBron James ... who was a spectator Monday night due to injury.

Get well soon!