With City's European venture over after coming unstuck against Liverpool in the quarter final stage to the tune of a 5-1 aggregate defeat, which culminated in a 2-1 second leg loss, Guardiola is eager to address his squad's successive shortcomings in the Champions League and build on the club's domestic superiority.
For the first half last week he drove the Liverpool midfield forward and was instrumental in all three goals.
European governing body Uefa had also charged Liverpool after fireworks were set off and objects thrown inside Etihad Stadium.
Guardiola was angry that Lahoz - with whom he has clashed before, when City played Monaco in the round of 16 last season - had ruled out Leroy Sane's first-half goal for offside when it should have stood because the ball came off Liverpool's James Milner, rather than City striker Gabriel Jesus, before the Germany winger scored.
But to be truthful, absolutely nobody saw this coming and the Catalan club are in a state of shock as they attempt to digest exactly what went wrong in the Italian capital. Yet the side didn't miss a beat.
On Saturday against United there was the bizarre sight of him ranting at Fabian Delph for turning back towards goal, apparently unaware the full back had then sparked a move which led to City hitting the post.
City understandably failed to maintain the intensity of their first-half display and Salah got the decisive goal when he followed up after Ederson had denied Sadio Mane with a wonderfully-judged chipped finish past the despairing Nicolas Otamendi in the 56th minute. Playing rigidly to principle is his greatest weakness.
For now, it has to be a case of licking the wounds for a day, then get back to work. The Premier League is hard to hack. No one on the City bench seemed to take charge and instruct players with any great passion. Last year's champions are looking like missing out on the top four.
Guardiola's obsession with the finer details has worsened. It was a while ago Liverpool was in the semis and I was in the semis and now we are there together."Guardiola admitted beforehand that his side needed the "perfect" performance and the hosts got the perfect start as they opened the scoring after just 117 seconds".