At InVasion, the Inaugural Brawl took place between Team WCW/ECW and Team WWF. The WWF consisted of Stone Cold Steve Austin, Kurt Angle, Chris Jericho, Kane, and the Undertaker, who all wrestled against the team of DDP, Booker T, Rhyno, and the Dudley Boys. Near the end of the match, all of the wrestlers were outside of the ring except Booker T and Angle. Kurt Angle applied the ankle lock on Booker T, who tapped out, but no referee was there to witness it. Stone Cold then dragged a referee into the ring, but then kicked Kurt Angle in the face, Stunned him, and placed Booker T on top of Kurt Angle and told the referee to count. Team WCW/ECW won the match due to Stone Cold's actions.
Shane McMahon, on the July 26 edition of "SmackDown!", extended an invitation to The Rock, who had not been seen since the "RAW" following WrestleMania X-Seven, to the Alliance. Also that night, Kurt Angle challenged Booker T to a WCW World Heavyweight Championship match, which Booker T accepted. The WWF gained momentum when Angle beat Booker T with an ankle lock, taking the WCW Championship away from the Alliance. Angle's title run proved to be short-lived, as Booker T won it back on the July 30 episode of "RAW".
On that same "RAW", The Rock returned for the first time since his suspension on the April 2 edition of "RAW". Shane and Vince McMahon were in the ring that night, and each tried to convince The Rock to join their respective side. Shane McMahon took the liberty of reminding The Rock of how Vince screwed him out of the WWF Championship earlier that year at WrestleMania and also in a steel cage match the day after WrestleMania. Vince McMahon replied that Shane was somewhat accurate in his accusations but ceded that it was wrong for him to back Stone Cold, as he was a rattlesnake that he should have known would eventually bite him. He promised to The Rock that he had no intention of screwing him if he returned to the WWF but also ceded that he could not promise that he never would; if it was good for business, he said, then he just might do it. He told The Rock that he was at least being honest with him and pleaded for The Rock to trust himself, stating that his future was with the fans and the WWF. The Rock, however, Rock Bottomed Vince McMahon and proceeded to shake Shane's hand, but he then proceeded to Rock Bottom him as well.
His return led to a WCW Title match between The Rock and Booker T at SummerSlam 2001, which The Rock won, marking the second time the WCW Championship belt changed sides to the WWF. At that same pay-per-view, Austin retained his WWF Championship against Angle after Angle won by disqualification.
The following "RAW" and "SmackDown!" showings featured primarily inter-promotional matches between the two companies. Austin stole Kurt Angle's medals during one of the shows, and on the August 30 edition of "SmackDown!", tied them to a cinder block and threw them in a river. The following "RAW", Debra and Stephanie bought a new truck for Stone Cold, but Angle came up from behind and nailed Austin in the back of the head with a pipe. He put a cinder block and rope in the truck, put Austin in it, and drove away on the truck. He threatened to throw Stone Cold into a river if he did not get a title shot. Austin complied and gave him a shot at the upcoming pay-per-view, Unforgiven. Angle said, however, that Austin was "still going into the water", but instead simply embarrassed Austin by throwing him into a kiddie pool.
The WWF gained even more momentum at Unforgiven, as The Rock retained the WCW Championship against Booker T, and Kurt Angle made Austin submit to the ankle lock, winning the WWF Championship from Stone Cold, putting both belts into the hands of the WWF.
There were several inter-promotional matches after Unforgiven. Furthermore, a crucial plot point formed when, on the October 8 airing of "RAW", Jericho and The Rock teamed up against Shane McMahon and Rob Van Dam. Jericho's face was drenched in blood and, with a steel chair in his hand, accidentally nailed The Rock when he was trying to hit Shane McMahon. This caused a stir backstage later on in the night when The Rock checked to make sure Jericho, who was being treated by EMTs, was in good condition but stated that Jericho made a big mistake in the match. Jericho, irritated, countered that everyone makes mistakes, including The Rock. The Rock responded that everyone should own up to their mistakes but was more concerned with Jericho's condition. As he went to leave the room, Jericho made a comment to the EMT wondering "what the hell" The Rock wanted for him. The Rock overheard this, walked back, and asked Jericho to repeat himself. Jericho did just that, and The Rock countered that his mistake actually cost them the match. Jericho countered that he maybe should have hit The Rock instead with a chair on purpose and proceeded to taunt The Rock by stating that he should knock the People's Eyebrow off of The Rock's face. The Rock provoked Jericho to do just that, and a brawl ensued.
Also that night, Stone Cold and Kurt Angle faced off for the WWF Championship, and William Regal, who sat at ringside to ensure a fair match would take place, hit Kurt Angle with the championship, thereby backstabbing the WWF and costing Angle the title.
The feud between Jericho and The Rock built up to a match at No Mercy on October 21, where Jericho beat the Rock to win the WCW Championship, and Stone Cold Steve Austin defeated Angle and Rob Van Dam to retain his WWF Championship.
On the October 29 edition of "RAW", Shane McMahon told his father, Vince McMahon, that a member of the WWF would jump ship to the Alliance that night. Later that same night, Kurt Angle backstabbed the WWF by hitting Jericho, The Rock, Undertaker, and Kane with steel chairs. On the November 1 edition of "SmackDown!", Angle, who originally led the WWF wrestlers, explained that he represented what is great about America—he was a winner, and his defection came from his decision to fight along the winning side. That side included Stone Cold, a man, Kurt Angle claimed, knew how to win.
On the November 5 airing of "RAW", Vince McMahon countered Kurt Angle's defection by stating that a member of Team Alliance would defect during a match at the upcoming Survivor Series. Stone Cold came out to confront Vince about it, and Vince stated that Stone Cold would be the one to defect. Because of this announcement, many Alliance members began to distrust Stone Cold, looking at him with suspicious eyes, to which Stone Cold denied the charges and called Vince a liar. Stone Cold went on to interrogate members of Team Alliance, questioning Booker T and sitting Rob Van Dam down in a room with a light shining on him.
All of this led to a "Winner Take All" match at Survivor Series 2001, which pitted Team WWF (The Rock, Chris Jericho, The Undertaker, Kane, and The Big Show) against Team Alliance (Steve Austin, Kurt Angle, Booker T, Rob Van Dam, and Shane McMahon). The final three men in the match were The Rock and Jericho vs. Austin. Jericho was eliminated and, to continue the feud between the two men, attacked the Rock, even though Jericho's future was on the line if The Rock lost. The Rock and Austin continued to battle it out, and the referee was knocked down in the match. Austin stunned the Rock and pinned him, but there was no referee to count it. Austin approached the downed referee to try to revive him. As this was occurring, Angle ran to the ring, picked up the WWF championship belt, and nailed Austin with it, revealing himself to be the defector to which McMahon was referring the entire time. The Rock followed this with a Rock Bottom and a pin on Austin, to which the referee woke up and counted Austin down to three. Team WWF prevailed, thus ending the storyline.