Sergio Aguero says Manchester City's hopes of defending their title look "a bit grim" after a 3-1 defeat away to Southampton on Saturday.
A series of defensive mistakes cost Roberto Mancini's side dearly at St Mary's Stadium and if Manchester United beat Everton at Old Trafford on Sunday they will go 12 points clear of City at the top of the Premier League table.
However, while Aguero could not disguise the disappointment of watching the title slide from City's grasp with each passing week, he has insisted they will keep fighting for the rest of the campaign.
"Some days, nothing works the way it should," he wrote on Twitter.
"(Saturday) was one of those days. There's no excuse - we need to work hard to forge ahead.
"It all looks a bit grim right now, but I won't believe giving up is an option."
Aguero scored 23 goals in the league last term, including the sensational last-gasp winner against Queens Park Rangers to hand City the title on goal difference, but he has only notched nine for Mancini's team so far this season.
Injured club captain Vincent Kompany was badly missed as the City back line struggled against Southampton but, he praised his side's fans for their support during the game despite the result.
The defender posted on Twitter: "Our fans sang and stood behind us all game yesterday, despite losing. Just reminds me that there will always be a lot to play for."