The Gunners went level on points with Premier League leaders Manchester City on Saturday with an impressive 3-0 win over Swansea City at the Liberty Stadium.
Goals from Laurent Koscielny, Olivier Giroud and a first effort for the club from Joel Campbell gave Arsene Wenger's men the points in Wales as they put aside their miserable League Cup exit at the hands of Sheffield Wednesday behind them in emphatic style.
The reverse to Wedneday aside, it's been a fruitful few weeks for the Gunners, who followed up victory over Bayern Munich with a win against Everton at the Emirates on October 24, and with Chelsea now a whopping 14 points behind City, Arsenal have emerged as the most likely challengers to Manuel Pellegrini's leaders.
Hartson, who played for the Gunners from 1995-1997, was impressed with Wenger's side's display against his hometown club, but the Welshman feels that they are still a couple of players short of landing their first league title since 2004.
Speaking on the BBC's Match of the Day show on Sunday, Hartson said that Wenger will need to dip into the transfer market to land a striker and a centre-back when the window re-opens in the New Year.
Hartson said: “If Arsenal add a couple of players then I think they will go close [to winning the league]. I think Manchester City are the team to beat at the moment and I think Arsenal need a centre-forward to help Giroud and Theo Walcott.
“Walcott is obviously injured now and I think they need a defender because I think Per Metersacker can be a bit brittle at times.”
Arsenal face a difficult looking assignment on Wednesday when they travel to Bayern Munich before returning to domestic duty on November 8 when they host local rivals Tottenham Hotspur in the North London derby.