Boateng and Richards add to City's growing defensive crisis

Manchester City's hopes of restoring lost momentum after the international break have been a dealt a blow with a mounting defensive injury crisis which is likely to deprive the club of Jerome Boateng and Micah Richards for much of the run-in.

Boateng arrived back in Manchester last night for tests today on knee cartilage damage sustained during the warm-up for Germany's win over Kazakhstan on Saturday which the national team doctor has already declared requires surgery. That would effectively mean Boateng's season is over, though City retain some hope that an operation will not be required on the lateral meniscus tear, as the German national camp's prognoses are often pessimistic.

Boateng looks unlikely to be a contender for the FA Cup semi-final with Manchester United on 16 April and the hopes being fostered by Richards that he will be back for that game, having suffered a hamstring injury in England Under-21's defeat of Denmark last Thursday, also look extremely slim. Richards is to install an oxygen chamber in his house in his race to be ready, though it will be a miracle if he plays against United. With Kolo Touré also sidelined pending a possible charge for taking an illegal substance, Roberto Mancini has increasingly limited options.

Pablo Zabaleta may be asked to deputise at right back, where Boateng and the in-form Richards have commanded the role virtually all season. Dedryk Boyata has also been used at right-back by Mancini in the home win against Chelsea, though it was his first senior game there and he has not been used in the Premier League since his dismissal in the fifth minute of the home defeat to Arsenal.

With Carlos Tevez also facing a race against time to be fit for the visit of Sunderland on Sunday – City remain hopeful he will win it – Mancini will be cursing an international break which he declared his palpably tiring squad was in need of. However, the timing of the training ground prank which saw Mario Balotelli throw a dart in the direction of a youth-team player is not as unfortunate as at first appeared. It is understood that the incident occurred a month ago, which is less grim for Balotelli who has only just been left out of Italy's international squad for his dismissal against Dynamo Kiev.

Meanwhile, Manchester United manager Sir Alex Ferguson is expected today to be present in the United States at an event to launch details of the club's tour of the US this summer which will conclude with a lucrative and mouth-watering encounter with Barcelona in Washington DC. United will begin their tour against New England Revolution in Massachusetts on 14 July, play Seattle Sounders in Washington state six days later, with matches against Chicago Fire and a repeat of last summer's fixture against the MLS All-Stars to follow before the meeting with Pep Guardiola's side on Saturday 30 July.