Ghana international Thomas Partey was sent off as Atletico Madrid bowed to a 3-1 home defeat to rival Real Madrid in Madrid derby at the Wanda Metropolitano on Saturday.
Partey was dismissed after getting his second yellow card at the end of a disappointing afternoon for Diego Simeone's side.
Sergio Ramos restored the visitors' lead with a penalty and Bale converted from Luka Modric's pass to ensure the win.
The defeat leaves Atletico Madrid in third place while Real Madrid have moved to second, five points behind Barcelona, who play Athletic Bilbao on Sunday. 
With a convincing victory in the Madrid derby on Saturday, Real Madrid returned to second place in the Spanish league for the first time since September and moved within five points of leader Barcelona, which has a difficult away match against Athletic Bilbao on Sunday.
In a derby marked by video review, Real Madrid defeated Atletico Madrid 3-1 at Wanda Metropolitano Stadium with an overhead kick by Casemiro, a penalty kick converted by Ramos, and a second-half goal by Gareth Bale.
Antoine Griezmann scored for Atletico, which lost at home for the first time this season. Diego Simeone's team stayed six points off the lead.
Griezmann's goal was initially disallowed for offside but the VAR reversed the call. Video review also had to be used to confirm the penalty that led to Ramos' goal just before halftime, and to verify another offside call that disallowed a second-half equalizer by former Real Madrid forward Alvaro Morata. It was also used when Morata wanted a penalty call — not awarded — later in the game.
Atletico, coming off its first league loss since the third round, played a man down from the 80th minute after midfielder Thomas Partey was sent off for a second yellow card.
The city rivals drew their last four league matchups, and Real Madrid's last win against Atletico was nearly two years ago in the Champions League semifinals.
Saturday's match was even when Casemiro opened the scoring with his an overhead kick after Atletico's defense could not fully clear a corner kick.
The VAR then helped Real Madrid by confirming a penalty decision after Vinicius Junior made a great run down the left side and was brought down from behind by Jose Maria Gimenez just inside the area. Ramos converted the 42nd-minute penalty.
Atletico thought it equalized again early in the second half after Morata — playing against his former club for the first time since joining Atletico — scored with a shot over Courtois, but he was immediately ruled offside.
Madrid sealed its fifth straight league win with Bale's low shot after a pass by Luka Modric in the 74th. Bale, who replaced Vinicius Junior earlier in the second half, appeared to provoke the Atletico crowd during his celebration near one of the sidelines.
Courtois, who used to play for Atletico, was loudly jeered from the start. Atletico fans threw stuffed rats toward the goalkeeper from behind one of the goals.