NL100: 77 vs unknown, call river?

$0.5/$1 No Limit Holdem

7 players

Converted at weaktight.com

Stacks:

Hero (UTG) ([="#0000cc"]$103.10[/])

UTG+1 ([="#0000cc"]$144.30[/])

MP ([="#0000cc"]$100.90[/])

CO ([="#0000cc"]$100.00[/])

BTN ([="#0000cc"]$8.90[/])

SB ([="#0000cc"]$99.00[/])

BB ([="#0000cc"]$133.49[/])

Pre-flop: ($1.50, 7 players) Hero is UTG 7DIAMONd 7:spade:

[="#cc0000"]Hero raises to $4[/], [="#777777"]5 folds[/], BB calls $3

Flop: 8:spade: 3:heart: 8DIAMONd ($8.50, 2 players)

BB checks, [="#cc0000"]Hero bets $5[/], BB calls $5

Turn: 3:spade: ($18.50, 2 players)

BB checks, Hero checks

River: 9:spade: ($18.50, 2 players)

[="#cc0000"]BB bets $18.50[/], [="#0000cc"] $18.5 to Hero ($94.1)?[/]

El oponente es desconocido -no sé si se acababa de sentar o algo, el caso es que no me salían sus stats- y no me suena haberle vsto por las mesas.

Alguien hace value bet en el turn? Call river?

Un saludo!