After a brief staredown where the camera zooms in on Darth Maul and Qui-Gon's face, both Qui-Gon and Obi-Wan charge Darth Maul -- but not before Obi Wan looks like he just got pelted in the forehead and goes "Ugh!"
(this is right before Maul back-flips to a higher bridge)
Better illustrated in this video
Perhaps Darth Maul did some weird Force thing off-screen, but it still seems very strange. What is happening here?