With the game at Camp Nou tied at one goal apiece and Barca down to 10 men following the dismissal of defender Gerard Pique, Keita put the hosts ahead with a stunning strike with just over 11 minutes remaining before Xavi sealed a crucial win just before the full-time whistle.
Keita's intervention in what was his first start since November had been key and Guardiola stated afterwards that he hopes that the Mali international, who has been linked with a move away at the end of the season, remains in Catalunya.
“He scored a golazo," the boss told reporters after the game. "This is a guy who never plays poorly and who always makes the right decision.
"There are many players who, when they lose the confidence of a coach, are offended. They feel that they are the centre of the universe and do not understand that the coach does it [drops them] for the good of the team.
"But one of the most wonderful things in these four years is to have met a guy like him.
"Today I'm happy that he has had such a huge game and scored a great goal. The work he does makes my job easier and I hope he will stay here as long as possible."
Guardiola, though, was also keen to pay tribute to the rest of his players for the heart and resilience they had displayed in difficult circumstances against Sporting.
“We won a match against a very defensive side in a match that turned against us," he mused. "I'm happy with how the players reacted. The players took a step forward tonight.
“It’s very necessary to win games like this throughout the year. The way this game was won reinforces our morale.
“We now have to try and enjoy our next game as we try to get to the quarter-finals of the Champions League for the fourth year in a row."
Barca take a 3-1 lead into the second leg of their last-16 clash with Bayer Leverkusen at Camp Nou on Wednesday night.
Since November, Goal.com has been publishing exclusive extracts from Graham Hunter's highly-anticipated new book, 'Barca: The Making of the Greatest Team in the World'. The very last extract, which was published last Friday, looks at Andres Iniesta's risky return from injury in the 2009 Champions League Final and how he was described by Wayne Rooney as the 'best midfielder in the world'. Don't miss it!