It is an impressive performance from Williams speedy Valtteri Bottas, just one minute left before the chequered flag, he puts fastest lap, 0.050s quicker than Hamilton, ahead of team-mate Felipe Massa and Nico Rosberg.
Valtteri Bottas becomes only the fourth driver to lead a P3 session this year, after the two Mercedes and Daniel Ricciardo.
Another impressive show from Toro Rosso’s Daniel Kvyat, he moves up to fourth between Massa and Rosberg.
The track was strongly packed around the short lap at the challenging Red Bull Ring, with just 0.079secs covering the first four and 0.2secs the top six.
McLaren’s Kevin Magnussen was eighth, with team-mate Jenson Button missing most of the session with brake problems.
Ferrari’s Kimi Raikkonen was ninth, again struggling compared to team-mate Alonso, 0.434secs adrift of the Spaniard.
BBC F1 analyst Allan McNish said: “We’ve seen a very close battle and it’s quite mouth-watering for this afternoon.
The usual people are at the front but there is a little bit of added spice in there.
“I think Mercedes still have a bit of an advantage but Williams could well be on the second row behind them.”