Italy 3-1 Argentina
(25-17, 21-25, 25-17, 25-23)
Italy are up and running in Pool A of the Olympic men's volleyball tournament after seeing off a dangerous Argentina side.
They lost their opener on Sunday - running in to a well-tipped Poland - but put that behind them today, dispatching their South American opponents who had impressively seen off Australia at the weekend.
Michal Lasko's spike finished the job for them, a fitting end after he had dominated at the net throughout, spiking 12 times and producing four kill blocks that shut Argentina down.
They did impress in taking the second set but, despite good reception figures, they were not potent enough close in, with only Facundo Conte (14 points) making an impression.
Italy next head for a clash with Great Britain, while Argentina are up against Poland on Thursday.
Poland 1 Bulgaria 3
(22-25 27-29 25-13 23-25)
Poland's title-winning hopes were handed a crushing blow by Bulgaria in an all-action European duel at Earls Court.
Andrea Anastasi's side had been installed as gold medal favourites by some after winning the World League, and appeared to be worthy of the tag as they took Italy apart in their opener on Sunday.
But Bulgaria, Great Britain's conquerors in their first game, beat them up by playing them at their own game, hitting them off the court with a simple down-the-middle approach.
Tsvetan Sokolov led the way with 28 points - Poland were unable to deal with him at the net, while his four aces were an added bonus for the world number nines.
The former beach volleyball partnership of Zbigniew Bartman and Bartosz Kurek responded with a combined total of 41 points but, shorn of support in other areas, they were unable to keep their side afloat.
They have a chance to get back on track against Argentina on Thursday, while Bulgaria will be favourites to extend their unbeaten record against Australia.
Serbia 3 Tunisia 1
(25-15, 25-21, 20-25, 25-18)
Serbia recorded their first win of the men's Olympic volleyball tournament as they saw off Tunisia at the start of the fourth day of competition.
Having been drawn against defending champions the United States first-up, Igor Kozakovi's men were realistically always waiting for today to get their campaign up and running and so it proved at Earls Court.
After easing into a 2-0 lead they let their African opponents back in, before closing the match out with ease in the fourth set.
Six-foot-seven Aleksandar Atanasijevic topped their scoring charts with 24 points - 19 of them on the spike - while Uros Kovacevic chipped in with 19 and Marko Podrascanin blocked eight times.
Hamza Nagga took 22 points away for Tunisia, but their inability to win points on their serve cost them.
They had just three unreturned, while Serbia recorded nine.
The Europeans are next up against Germany while still-to-win Tunisia take on Russia.