Manchester City midfielder Kevin de Bruyne faces another spell on the sidelines after picking up a hamstring injury in Saturday's 1-0 Premier League win at Bournemouth.
The Belgium midfielder went down after playing a pass in the first half at the Vitality Stadium and was promptly substituted by manager Pep Guardiola.
His replacement, Riyad Mahrez, scored the only goal of the game to send City back to the top of the Premier League.
City's medical department will assess the severity of De Bruyne's injury on Sunday, but the way he went down with no Bournemouth player in proximity will heighten fears of De Bruyne facing another prolonged spell out.
De Bruyne was one of the standout performers for City in their 2017/18 championship-winning campaign with 12 goals and 21 assists in all competitions as Guardiola's squad set new benchmarks, including most points, wins and goals in a Premier League season.
By comparison, the influential playmaker has managed only 14 league appearances this campaign, with one goal and assist.
Guardiola also replaced centre-back John Stones with Vincent Kompany at half time against Bournemouth, although the City manager said that change was made as a precaution with City's upcoming fixtures in mind.
"Kevin will be out for a while with a muscular problem - hamstring. John I think is more precaution. We didn't take a risk, we'll see tomorrow," Guardiola said.
Guardiola suggested City's busy schedule, as they compete for trophies in three competitions having last month secured the League Cup with a shoot-out victory over Chelsea, has not helped.
"I think we've played 25 games in 93 days, one every three days, so it's a physiological issue," the Spaniard added. "The body is not able to recover so sometimes the muscle says 'hello, that's enough'.
"We don't give players time to recover. We play a game, then after, when they are not recovered, we play another game. There is only a short amount of time and it is very demanding. But everybody's committed and we'll wait for Kevin to come back."
City's upcoming fixture list is a congested one with three fixtures in as many competitions in eight days. After hosting Watford in the league on Saturday City face Schalke in the return leg of their Uefa Champions League last-16 ties at the Etihad the following Tuesday - City hold a 3-2 advantage over the Germans from the first leg - before a trip to Swansea City in the FA Cup quarter-finals on March 16.
City announced on Sunday that defender Eliaquim Mangala has signed a one-year contract extension until 2020.
The 28-year-old France international Mangala joined City from Porto in 2014 and has made 81 appearances during his time at the Etihad Stadium.
Mangala picked up a Premier League winners' medal after playing nine top-flight games for Guardiola's side during the first half of last season.
He spent the 2016/17 campaign on loan at Valencia before moving on loan to Everton in January 2018.
Injury cut short his spell at Goodison Park and he has not made a first-team appearance since February last year.
