The USA held on for a 13-6 win over World Cup debutants Russia in an enthralling encounter in New Plymouth on Thursday.
Intensity was the name of the game as the protagonists went at each other hammer and tongs.
The USA led 10-3 at the break thanks to a fantastic try from scrum-half Mike Petri but had to wait until deep in the second half to add a penalty to give themselves some breathing room.
A late penalty from Russian however set up a grandstand finish.
Despite what the scoreline might suggest, there was plenty of good rugby on offer. Unfortunately the very wet conditions did not help as driving rain, in the second half in particular, made handling very difficult.
The Bears made a storming start to the game and looked dangerous when putting some of their big runners in space.
But the World Cup newcomers were half a yard behind their rivals for much of the game and one would imagine that in more favourable conditions the USA would have won more confortably.
After being handed a beating in the scrums against Ireland, the Americans would have enjoyed holding the upper hand in the set pieces, particularly in the line-outs.
Indeed, the Russians were denied a handful of opportunities as they failed to secure possession on their own throw. In total, the USA stole six of the opponents' throw-ins, enough to stifle the red armada's momentum.
Russia opened the scoring after just three minutes when fly-half Yury Kushnarev slotted a penalty. The Russians had come racing out of the blocks and had the American defence working overtime.
A penalty from USA full-back Chris Wyles levelled matters before the more experienced team struck with the game's only try from a flowing move started inside their own half to put Petri over the line under the posts at the end of the first quarter. Centre Andrew Suniula put fly-half and brother Roland through a hole and the ball was worked back inside for Petri to drag Igor Klyuchnikov over the line, Wyles added the conversion.
That gave the Americans a seven-point led but despite largely controlling the match, they were not able to move further ahead until the 64th minute due to a combination of gallant defending from the Russians and some below-par handling from the blue-clad outside backs.
Russia finished strongly and a silly shoulder charge from US skipper Todd Clever allowed Kushnarev to add his second three-pointer and set up a nail-biting finish.
The Bears were unable to produce the accuracy needed to come up with a try however and must settle for a losing bonus-point in their first RWC appearance.
Man of the match: The US dominated the breakdown zone and Mike MacDonald put in plenty of graft as well as being solid at scrum time.
Moment of the match: No doubt about this one, the USA try was one of the best we've seen in the tournament so far as they turned on the gas to break from their own territory.
Villain of the match: A few fisticuffs, as you would expect, but a villain award seems a bit harsh.
Pens: Kushnarev 2
Pens: Wyles 2
Russia: 15 Igor Klyuchnikov, 14 Vladimir Ostroushko, 13 Konstantin Rachkov, 12 Alexey Makovetskiy, 11 Vasily Artemyev, 10 Yury Kushnarev, 9 Alexander Shakirov, 8 Vyacheslav Grachev, 7 Artem Fatakhov, 6 Andrey Garbuzov, 5 Denis Antonov, 4 Alexander Voytov, 3 Ivan Prishchepenko, 2 Vladislav Korshunov (c), 1 Sergey Popov.
Replacements: 16 Valery Tsnobiladze, 17 Alexander Khrokin, 18 Vladmimir Botvinnikov, 19 Adam Byrnes, 20 Victor Gresev, 21 Alexander Yanyushkin, 22 Andrey Kuzin.
USA: 15 Chris Wyles, 14 Takudzwa Ngwenya, 13 Paul Emerick, 12 Andrew Suniula, 11 James Paterson, 10 Roland Suniula, 9 Mike Petri, 8 Nic Johnson, 7 Todd Clever (c), 6 Louis Stanfill, 5 Hayden Smith, 4 John van der Giessen, 3 Matekitonga Moeakiola, 2 Chris Biller, 1 Mike MacDonald.
Replacements: 16 Phil Thiel, 17 Shawn Pittman, 18 Scott LaValla, 19 Pat Danahy, 20 Tim Usasz, 21 Nese Malifa, 22 Blaine Scully.
Venue: Stadium Taranaki, New Plymouth
Referee: Dave Pearson (England)
Assistant referees: Craig Joubert (South Africa), Carlo Damasco (Italy)
Television match official: Graham Hughes (England)