Cristiano Ronaldo's bout of tristeza is the least of José Mourinho's problems. The world's second best footballer may be flaunting his supposed sorrows, but at least he is still doing his best for Real Madrid on the pitch. According to Mourinho, the same cannot be said for a number of his team mates.

Halfway through a 1-0 defeat at Sevilla's Ramón Sánchez Pizjuán stadium on Saturday, Mourinho found it necessary to withdraw Angel di María and Mesut Ozil, two of the brightest sparks of the attack which carried the club to the Spanish championship last May. Neither was injured. Afterwards the manager said he regretted only that he was limited in the number of replacements he could use. Otherwise it might have been seven.

The seriousness of his disquiet was made even plainer when the players reported for training on Sunday to discover Ozil was being banished to work with the substitutes. Since the playmaker of Joachim Löw's Germany had started all but one of Madrid's competitive fixtures this season, it seemed clear to whom Mourinho had been referring when he questioned the commitment of some of his players.

After a week in which Madrid announced that it had just become the first football club in the world to top €500m in income for a single season, Mourinho sees his squad languishing in 11th place in La Liga. After a mere four matches, they already trail Barcelona by eight points. The shine has gone from their two-leg victory over their Catalan rivals in the Spanish Super Cup last month.

For the Portuguese, a yield of four points from four matches represents the worst start to a league season of his entire career. A 3-0 home win over Granada, a 1-1 draw with Valencia and defeats at Getafe and Sevilla in the last month do not comprise the sort of run to please a manager whose opening four games in his first 10 seasons in management – with União de Leiria, Porto, Chelsea, Internazionale and Madrid – yielded only a single defeat to set against 30 wins and nine draws.

If they lose to Manchester City in the Santiago Bernabéu on Tuesday it will be the first time in their history that the nine-times European Cup champions have fallen to defeat in their first home match of the competition, a record consisting of 40 wins and two draws, the most recent of which came against Anderlecht, exactly 50 years ago.

Several reasons are being advanced to explain their current sluggishness. One is an alleged lack of fitness throughout the squad, possibly generated not just by the Euro 2012 finals but by a pre-season programme that included a trip to the United States.

Another is a sudden weakness in defence against set-pieces. In the matches with Valencia and Getafe they proved fatally vulnerable to free-kicks from wide positions and the goal that sank them on Saturday came when Sevilla won a corner in the second minute and Piotr Trochowski steamed in ahead of the dozing Di María to drive a powerful volley past Iker Casillas. Madrid's goalkeeper, their talismanic captain and so often their saviour, has also been under scrutiny for uncharacteristic errors.

The lack of goals throughout the attack is another problem. Of their five league goals this season, three have come from Gonzalo Higuaín and two from Ronaldo, with none from Ozil, Di María, Karim Benzema or Luka Modric, although the new £33m acquisition from Tottenham Hotspur managed to hit the post after replacing Ozil against Sevilla.

Benzema's barren spell is particularly surprising: after an indifferent start to his career at the Bernabéu, he came good with 32 goals in all competitions last season, prompting Mourinho to speak of his "transformation." But his failure to score in four matches for France during the Euro finals means that his most recent goal for club or country came against Mallorca on 13 May.

None of the side's faults, real or imagined, can be laid directly at Ronaldo's door, although his remarks after the victory over Granada can hardly have helped to keep morale high. "I'm a little sad," he said when asked why he had failed to celebrate his two goals. "When I don't celebrate, it's because I'm not happy. People at the club know why."

It was not, he said, because Barcelona's Andrés Iniesta had just been voted European player of the year. It was nothing personal. It was a "professional" matter.

This led most observers to conclude that Ronaldo was feeling the need for an enhanced contract, something to lift him closer to the top of the world's 10 best paid players, currently headed by Samuel Eto'o, whose €20m-a-year from Anzhi Makhachkala is double Ronaldo's emolument.

That could provoke a second financial crisis for Florentino Pérez, Real's president, who is said to be preoccupied by the effect of Spain's economic meltdown on the health of his construction business. A footballer's salary demands are likely to be easier to resolve, and Manchester City would be foolish to assume that Madrid's indifferent league form will ease their path tonight.