(REUTERS) - Manchester City's Pep Guardiola is mired in the worst run of his managerial career but is confident the English Premier League leaders have the quality to bring an end to, and avoid a repeat of, their current six-game winless streak.

City started the season by winning their first 10 games in all competitions but the momentum has stalled in recent weeks, and Wednesday's 0-1 loss to Manchester United in the League Cup fourth round marked their sixth straight game without a victory.

"We will improve. Sometimes it happens in football that the managers don't win," Guardiola told British media, adding that he had never been through such a run as a manager.

"It is the first time... and hopefully it does not happen again.

"But it is part of our profession, sometimes you win and sometimes lose. I have learnt in all the 16 games.

"Every team has streaks of good results and bad results. The strange thing is after seven years as a manager, it happens now."

The Spaniard also said Vincent Kompany was withdrawn at half-time on Wednesday due to fatigue, not a new injury.

"He told us he is tired and not ready to play the second half," said Guardiola, adding that it was a positive step that the injury-plagued central defender was getting game time and not breaking down again.

City, who have seen their lead at the top of the Premier League evaporate and are ahead of Arsenal and Liverpool only on goal difference, travel to face 13th-placed West Bromwich Albion on Saturday.