A football player is pursuing the opposing teams quarterback, who is about to throw the ball.
They are playing football
Football players performing actions like pursuing an opposing team's quarterback is playing. The quarterback's being about to throw makes it plural, both teams playing football.
exists e1 p1 s1 s2 x1 x2 x3 x4 x5 x6.(n_ball(x6) & n_team(x3) & a_opposing(s1) & Theme(s1,x3) & Theme(e1,x3) & Actor(e1,x1) & v_pursue(e1) & Topic(s2,p1) & Actor(s2,x5) & a_about(s2) & exists e2.(Theme(e2,x6) & Actor(e2,x5) & v_throw(e2)) & (x3 = x5) & Time(x3,x4) & n_quarterback(x4) & n_player(x1) & of(x1,x2) & n_football(x2))
exists e1 x1 x2.(n_thing(x1) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_football(x2))