He will have little time to settle in to his new surroundings before the campaign starts on Saturday, but with a full pre-season from Liverpool under his belt, he does not envisage any problems.
"I'm very excited," he told West Ham TV. "it's a great opportunity for me being here, it's a great Club, a good manager to play for and I'm really excited to get going.
"I'm ready and I'm fit [for Cardiff City]. I've played a decent few games for Liverpool in pre-season, so there will be no problems on that front.
"It's all happened quickly in the last couple of days, shooting down here and getting things sorted, but I'm really excited and hopefully I'll play some part on Saturday."
Downing admitted he did not need too much persuading to join up with the Hammers once their interest became clear.
He continued: "I met the players and the manager on Monday. He's a really good, straightforward manager. I like him, I like the way he wants to work and I'm excited by what his plans are for the team as well.
"Sam didn't have to say much. You can see it's a great Club with passionate fans. The only thing he said to me were his plans for the team and how he wants to play and I'm excited by that and hopefully I can contribute in a good way this season.
"With the strengths of the forward players, crossing will obviously be a strength of the team. My aim is just getting back to playing regularly and playing well, like I did at Aston Villa, get a few goals and hopefully we'll have a good season."
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