Sweden's Anna Nordqvist holed-in-one to clinch a morning point in style as Europe tightened their grip on the Solheim Cup and the United States' tempers frayed during a controversial second day in Parker, Colorado on Saturday.
Europe opened up a 10.5-5.5 lead over the U.S. at the close, dominating the fourballs on an afternoon marred by an astonishing tiff over ball placements between the American pairing of Morgan Pressel and Cristie Kerr and their opponents Karine Icher and Beatriz Recari.
Relations, already strained in the morning when organisers admitted to a mistaken ruling in Europe's favor during Friday's play, became acrimonious as Pressel and Kerr quarreled with Icher and Recari on the 16th hole for over half an hour.
Officials needed to step in to place Recari and Kerr's balls after both shot into a water hazard and could not agree on each other's ball placement.
Icher and Recari shrugged off the furor to help Europe sweep the fourballs 4-0 and open a commanding five-point lead heading into Sunday's singles.
No team has ever rallied from more than two points behind to win the trophy, but U.S. captain Meg Mallon refused to concede.
"Obviously, it was a very disappointing afternoon," Mallon told reporters. "We have our work cut out for us tomorrow. It can be done. It's daunting right now but it can be done."
Trailing 5-3 after the opening day, the U.S. had pulled within a point after winning the morning foursomes 2.5 to 1.5, but Nordqvist, playing with Caroline Hedwall, fired up the Europeans by acing the 187-yard par-three 17th at Colorado Golf Club.
That sealed the clash with Pressel and Jessica Korda 2&1, and marked the Swede as the first player to make a hole-in-one in the tournament's history.
"I don't think it has hit me yet," Nordqvist said. "It was a really good shot, going straight at it. We thought it might be a little long, but it pitched and hit, and it's just an unbelievable feeling."
Stacy Lewis and Paula Creamer prevailed one-up over Azahara Munoz and Icher, while Michelle Wie and Brittany Lang won 2&1 over Suzann Pettersen and Beatriz Recari to give the U.S. early momentum in the foursomes.
The Americans were up in arms after organizers confirmed in the morning that Europeans Pettersen and Carlota Ciganda were given a favorable and incorrect ruling on the par-five 15th during their duel with Lewis and Lexi Thompson on Friday.
Ciganda hit her second shot into a water hazard and was allowed to take an incorrect drop before eventually halving the hole and going on to win the match.
The LPGA apologized "for any confusion" in a statement, but Lewis, who had argued the point with officials on Friday, was not mollified.
"It hurt us. It hurt our team. It hurt the momentum," she said. "But ... it fired us up more. So, if anything, if they feel bad about it, that's good, because we're just more fired up out of it."
Catriona Matthew and Caroline Masson salvaged a half for Europe in the morning foursomes against Britanny Lincicome and Lizette Salas, before Europe tore through the afternoon.
Jodi Ewart-Shadoff and Charley Hull won two-up over Creamer and Thompson, and Munoz and Ciganda prevailed one-up against Gerina Piller and Angela Stanford.
Hedwall and Masson won 2&1 over Wie and Korda, before Recari and Icher completed the sweep with a one-up win over and Kerr and Pressel following their 16th hole squabble.
The U.S. will need a monumental effort on Sunday to score the 14.5 points needed for victory, effectively nine out of the 12 singles battles.
Europe's five-point lead is the equal biggest in the competition's history heading into Sunday.
(Reporting by Ben Everill; Editing by Ian Ransom)