McIlroy's comeback stalled when he missed a birdie putt from the fringe at the 17th, and Peter Uihlein won, 2 and 1.
Thomas is projected to assume the world number one ranking from fellow American Dustin Johnson if he makes the final on Sunday but he will have to overcome 35th seed Watson, a two-times U.S. Masters champion who won the Los Angeles tour stop at Riviera last month.
Thomas and Stanley are joined in the quarter finals by Bubba Watson, Kiradech Aphibarnrat, Cameron Smith, Alex Noren and Kevin Kisner.
Casey only needed to halve his match against Matt Fitzpatrick to win his group for the third time in four years.
Watson, who is set to delay a planned family break after his unexpected advance through to Sunday, said on pgatour.com: "I keep advancing, and that is the key. I'm excited about it - it should be good".
"His bad holes I didn't mess up and I made a few birdies to throw in there", Kisner said.
His improved health has dovetailed with his increasingly better play at Austin Country Club and he's now two matches away from winning his first World Golf Championship.
However, it was all square when Thomas took the par-five sixth, only for the match to go into the turn all square again.
"But at the end of the day, obviously I didn't play very well, but I definitely didn't give him the match".
Thomas had won all five games at Austin Country Club this week, but he met his match in the form of Watson, who won 3 and 2 to reach the final for the first time in his career.
Kisner, meanwhile, ended Noren's impressive run in the tournament in a high-quality match that went to extra holes, with neither player leading by more than one hole throughout.
The world's second-ranked player was almost ideal the rest of the way, regaining the lead with three birdies in four holes starting at No. 5 and closing Stanley out with a bogey-free finish.
A day after shooting an 8-under 64 to open the big lead, Kerr had a 75 to drop a stroke behind playing partner Lizette Salas, Ji Eun-hee and Kim In-kyung.
"I wish I was hanging around for the weekend, but I'll rest up and get a little bit of work in before going to Augusta", McIlroy said.
But Spieth bogeyed the par-three 11th to hand the lead back to Reed, who stretched the gap with a gain on the 13th and then found himself three up after Spieth missed from six feet on the 15th.
"I don't know what's going to come with it", Thomas said. Charles Howell III and Ian Poulter both need to move into the top 50 after this week to earn a spot at Augusta National. "I hung in there and made putts and got it done in the playoff".
A number of worldwide human rights organizations have condemned her arrest and called for her immediate release. Elor Azaria, the Israeli soldier who executed a wounded Palestinian, will serve 9 months in jail.
The government's crushing offensive killed almost 1,500 people and wounded more than 5,000, according to opposition activists. Office for the Coordination of Humanitarian Affairs (OCHA), during a news conference in Geneva.
This will eventually include non-stop flights from Australia's eastern seaboard to Europe in an effort dubbed "Project Sunrise". History has been made following the departure of Qantas' first Perth to London flight on Saturday night.
Anderson wrote in a separate tweet that the domain where app data was being sent is classified as a phishing link by G-Data. Prime Minister Narendra Modi often uses the NaMo app to connect to the public and get their feedback on various issues.
Lawmakers on Capitol Hill are backing President Trump's decision to impose tariffs on China as Beijing threatens to retaliate. Trump's technology order is in response to "unfair and harmful acquisition of U.S. technology", said a statement by the U.S.
They pretended to be professors at other schools expressing interest in their academic articles, the indictment stated. With a motive of stealing expensive research, these nine accused tried to hack into 320 universities in the US.
While many Republicans have chosen to ally themselves with RNC leadership, principled conservatives like Mr. Lindsey Graham (R-SC) told CBN News, "We should just stick things in and make them vote against it".
State news agency MENA quoted al-Nemr as saying that two people, a policeman and a driver, were killed in the blast. Attacks in recent years were claimed by Islamic State in a targeted campaign against security forces and civilians.
The bill also does not defund so-called "sanctuary cities," something the White House specifically called on Congress to do. Trump repeatedly invoked the need to rebuild the USA armed forces to defend his signing of a bill that he was unhappy with.
For Daniel Ricciardo , the Australian Grand Prix has been an exasperating mix of desperately willing fans and mostly unwilling cars.
Islamabad United wins Pakistan Super League
However, the PCB continued in its efforts to convince foreign nations to begin touring Pakistan. -AP Cricket fans display their tickets as they stand in a queue to enter the stadium.
Saudi Arabia's crown prince meets Trump
A key focus of his visit will be any information on a potentially lucrative listing of up to 5 percent of Saudi oil firm Aramco . He's showing reporters a sign that lists Saudi purchases and another of pending sales of military equipment to the kingdom.
A Big Theme From Chicago's March For Our Lives: Change
Relatives of the victims of a deadly 1996 school shooting in Scotland were among the hundreds protesting Saturday outside the U.S. She said government has "extremely failed" to protect students from gun violence and she wants restrictions on automatic weapons.
Former Michigan players react to Final Four berth
Florida State: The loss ended a remarkable March for Hamilton's Seminoles, who hit their stride at the ideal time. Loyola-Chicago is the real deal on both offense and defense and they should be able to keep this one very close.
Iowa family found dead in Mexico resort of Tulum
Kevin was on the racetrack's board until past year when he stepped away to spend more time with his family, Baldwin said. Louis to arrive on Thursday in case the Sharps had just planned to stay an extra day, Weland told ABC News .
It's good that the Trump White House is so leaky
It is ironic that the very existence of this unconstitutional tool meant to plug White House leaks was exposed by the press. The Washington Post reported Sunday that Trump required his staff to sign the agreements, which extend past his presidency.
Trade Wars: USA Vs China
That measure had not targeted Chinese imports alone. "And they'll be paying more because the US economy won't be growing as much". Last year, American farmers exported $1.1 billion of pork products to China and Hong Kong, making it the No. 3 market by value.
Playboy model claims she had 10-month affair with Trump
For instance, Stormy Daniels' is a non-disclosure agreement which prevented her from talking about her relationship with Trump . Trump pointed out a room which he described as " Melania's room", saying "she likes to have her alone time" there.