(CNN) - Manchester City won the English Premier League title on Sunday after rivals Manchester United stumbled to defeat against relegation-threatened West Bromwich Albion.
Jose Mourinho's United team had needed to win against West Brom to keep the title race alive but surprisingly lost at home as Jay Rodriguez's header gave the league's bottom side a 1-0 win at Old Trafford.
On Saturday, City had convincingly beaten Tottenham Hotspur 3-1 and manager Pep Guardiola said he was going to play golf with his son rather than watch United play West Brom.
Guardiola's team has lost only two league games this season and if they win their remaining five games would end the campaign with 102 points.
On April 7, City played United and leading 2-0 at halftime had looked on course to claim the title. But Mourinho's team produced a stunning comeback to win the game 3-2 and put their rival's celebrations on hold.
Soon after United''s defeat on Sunday, the City website tweeted: "Our Time. Our City. Premier League Champions 17/18."
Mourinho acknowledged that "City were the best team" in the Premier League, telling the BBC: "Sooner or later they would get the points, so no dramas when the best team wins the league."
A serial winner as a manager with Barcelona and Bayern, Guardiola ended his first year in England at City without silverware -- his only failure to win a trophy since his managerial career started back in 2007.
Fast-forward to Sunday April 15, 2018 and Guardiola's City side has achieved a domestic double, adding the Premier League to the League Cup they won in February.
"Champions!!!!!! What a great feeling!! So happy to be able to share another trophy with our amazing fans!" tweeted City's captain Vincent Kompany.
Last week City exited the Champions League after losing their first and second leg quarterfinal ties to Liverpool, but in the Premier League, Guardiola's team has looked a class apart, scoring 93 goals in 33 games.
Guardiola is the first Spanish manager to win the Premier League, while City also tied United's record by winning the competition with five games to spare.
Former England international Gary Lineker, who now works as a television presenter, tweeted: "Congratulations to @ManCity on winning the Premier League title. Thoroughly deserved and won with a style of football that is truly joyous to watch. Well played."
READ: Salah faces emotional return to Roma
READ: Real Madrid to face Bayern Munich
'I believe in myself, says Mourinho
Meanwhile Mourinho was left counting the cost of an insipid display by his team.
"We were masters in complication, everything was complicated," Mourinho told Sky Sports.
"We didn't want or played simple, everything was slow, one more flick, trick, turn. There was no fluidity. We did not deserve to lose, we gave them opportunity to win the match."
This is Mourinho's second season at Old Trafford and he insisted that his impressive managerial record -- at Porto, Chelsea, Inter Milan and Real Madrid -- shouldn't be forgotten.
"I trust in my work. Eight titles. Three Premier League. Last not 20 years ago, it was three. I know how to win. I believe in myself. You don't win titles with inconsistency. You need consistency at every level. The mental level, day by day."
Mourinho and United still have a chance of winning a trophy this season -- the FA Cup -- and on Saturday face Spurs at Wembley stadium in the semifinals of the tournament.