Scotland turned on the style in the second half and ran in five tries to beat USA and leapfrog South Africa in Pool B. USA led at the break and had Scotland rattled with some big hits, but the home nation showed their class in the end to finish comfortable winners.
Ten points from 10 places Scotland in a perfect position to advance to the quarter-finals, with South Africa and Samoa still to face them.
Tries from Tim Visser, Sean Maitland, Willem Nel, Matt Scott and David Weir were complimented by 14 points from the tee to set up the crucial win.
USA opened the scoring early on from a penalty and they scored the opening try of the game to leave Scotland on the back foot.
Finn Russell was carried off on the hour mark and the loss the talented fly-half will be a big miss for Scotland, should the injury be a serious one.
The USA started on the front foot, and they took the lead on three minutes through the boot of Aidan McGinty, who floated over a try from just past the half-way line.
Scotland were not behind for long, and Stuart Hogg stepped up to the tee to level the score on seven minutes.
Following a staccato opening 10 minutes, the home nation began to express themselves and looked threatening down the middle in pursuit of a try. They settled for three points, and fly-half Finn Russell edged them ahead from just in front of the posts.
Hogg was unable to stretch the lead further on 18 minutes with another long-range effort drifting wide of the target.
That proved costly, as USA worked the ball swiftly upfield from a lineout and a big effort from the forwards allowed Titi Lamositele to barge over the try line. McGinty made it a seven-point score with his conversion kissing the post on its way through.
Brilliant footwork from Hogg looked to be the precursor to a certain try, but Tim Visser failed to collect the pass by fumbling the ball forward on the overlap when clear through.
Much of the battle was then contested in the middle third of the pitch, with the physicality ramping up from both sides.
The Americans continued to put in the big hits, but Russell failed to reduce the deficit to one point from a soft penalty, conceded for a man being beyond Chris Wyles’ kick.
Hayden Smith then put in a monster hit on Peter Horne which was met by a chorus of boos from the crowd.
The Eagles ended the half as they began it with their tails up, and they settled for a further three points after threatening to score a second try, to make it 6-13 at the break.
Almost immediately after the restart, Visser made amends for his bodged gather in the first half to collect on the overlap to run in Scotland’s first try of the day. Russell once again failed from the tee as his conversion attempt swerved wide.
A second try soon followed from Sean Maitland scoring the 100th of the tournament. Russell made no mistake this time from under the posts to put Scotland back ahead at 18-13.
McGinty then closed the gap back down to two from a USA penalty, but they almost conceded another try straight away but for some brilliant defending.
Substitute Willem Nel found the third try following the introduction of usual captain Greg Laidlaw, with the powerful prop reaching out a paw to place the ball just inside the left hand post.
Russell pulled up with the clock approaching the hour mark, and the fly-half had to be assisted off and replaced by Duncan Weir.
Another replacement scored the bonus try, with Matt Scott dancing through to snipe in from close range and seal the Scottish victory.
USA thought that they had registered a second consolation try, but Samu Manoa’s attempt was just held up. Oli Kalifi then agonizingly fumbled the ball forward from another great attack from the Americans, and the Scots were able to clear their lines with a penalty.
Weir put the icing on the cake of a solid Scotland display with try number five, and Laidlaw rounded it off for a 39-16 win.
What comes next:
It’s the big one, as Scotland face two time Champions South Africa in what could be a straight shootout match to top Pool B. Should the home nation fail to topple the Springboks, they must then defeat Samoa in their final group clash. Scotland have given themselves the best possible chance of qualifying and their fate is in their own hands, but it will be a big ask to inflict a second Pool defeat on a rejuvenated South Africa.
USA remain pointless in the Pool and with South Africa and Japan still to come, they may well end the tournament that way. One thing that this side does not lack is heart, and they will look to continue their run of scoring at least one try against every opponent in this year’s tournament.
Man of the match- Stuart Hogg
The all-action full-back was everywhere for Scotland in a tough test against the USA. Hogg scored a long range penalty to level the match up early on, and he made two clean breaks, with Visser unlucky not to finish off a gloriously created chance. Hogg also made 58 metres, two offloads, and was a threat all afternoon for the spirited Scots.
Scotland: 15. Stuart Hogg; 14. Sean Maitland, 13. Mark Bennett, 12. Peter Horne (Matt Scott 55), 11. Tim Visser, 10. Finn Russell (David Weir 60), 9. Henry Pyrgos (Greg Laidlaw 53); 8. Ryan Grant (Alasdair Dickinson 4), 7. Fraser Brown (Ryan Wilson 46), 6. Jon Welsh (Willem Nel 40), 5. Richie Gray, 4. Grant Gilchrist (Tim Swinson 18), 3. Alasdair Strokosch, 2. Ross Ford (Kevin Bryce 78), 1. Josh Strauss
USA: 15. Chris Wyles; 14. Takudzwa Ngwenya, 13. Seamus Kelly, 12. Thretton Palamo, 11. Blaine Scully (Folau Niua 59), 10. AJ MacGinty, 9. Mike Petri (Shalom Suniula 50), 8. Samu Manoa, 7. Andrew Durutalo (John Quill 59), 6. Al McFarland, 5. Greg Peterson (Danny Barrett 49), 4. Hayden Smith (Cam Dolan 43), 3. Titi Lamositele (Chris Baumann 68), 2. Phil Thiel (Zach Fenoglio 64), 1. Eric Fry (Oli Kilifi 66)