How Could He Make The River Call?

[popsy]

This is above my pay grade. It is a hand I observed on Pokerstars, involving one of the best players on Stars. Twin-caracas was CO with 5h4d. SB had AhKd. How could he possibly know the fives were good on the river?
PokerStars No-Limit Hold'em, $10 BB (8 handed) converter

CO($1298.75)
Button ($1911)
SB ($1122)
BB ($2560.75)
UTG ($377)
UTG+1 ($220.50)
MP1 ($725)
MP2 ($552)

Preflop: TC is CO with 5h,4d . Fold to CO, who
bets $40. SB raises to $100, CO calls.

Flop: ($15) T[img]/images/graemlins/spade.gif[/img], 2[img]/images/graemlins/heart.gif[/img], 5[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(8 players)</font>
<font color="#CC3333">SB bets $70</font>, CO calls $70.

Turn: ($155) 7[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(8 players)</font>
<font color="#CC3333">SB bets $120</font>, CO calls $120.

River: ($395) 7[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(8 players)</font>
<font color="#CC3333">SB bets $832 (All-In)</font>, CO calls $832.

Final Pot: $2059