The Blues won the top-flight crown with two games to spare last season after finishing seven points clear of runners-up Tottenham Hotspur.
The defending champions lost their Premier League opener at Stamford Bridge following a 3-2 defeat at the hands of Burnley.
Chelsea had the chance to move level on points with Manchester City at the top of the table on Saturday evening.
However, former Blues midfielder Kevin De Bruyne scored a second-half winner to secure three points at Stamford Bridge.
Manchester City and Manchester United have both earned 19 points so far following six victories and one stalemate to leave the duo five points clear of third-placed Tottenham.
Former Red Devils midfielder Giggs believes Manchester City and Manchester United are the teams to catch in the title race.
“I think Chelsea will still be in the mix but you’ve got to say City and Manchester United have been impressive and are the teams to beat,” Giggs told Sky Sports.
“I think we are seeing the managers, Pep Guardiola and Jose Mourinho, imprinting their own visions on their teams. In Pep’s case, with the goals they score and the chances they are creating, it’s exciting for City fans right now.”
Manchester United finished in sixth place in the Premier League table last season but won the EFL Cup and the Europa League in Jose Mourinho’s first season.
The Red Devils signed three players in the summer transfer window following the additions of Victor Lindelof, Nemanaja Matic and Romelu Lukaku.
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