The Daily Star says Ecuador striker Valencia is expected to finalise his move from Mexican club Pachuca to Upton Park in the next 24 hours after arriving in London late on Saturday night.
Downing said: "For large amounts of last season we played without a striker so we do need options. We can't rely on Andy (Carroll) all season.
"Andy was the big signing, but he struggled with injuries last season so hopefully the new signings will take the pressure off him a little bit.
"We need competition for places so if we do get that new signing then he will be a good addition to the squad and it's a big boost for the club.
"It's definitely good to hear there are more signings coming in. It's good for the fans too. They will get excited that they see there are new players coming in. The manager has stressed that they are more players to come.
"If we do get Valencia from what I've seen of him playing he looked a very good player.
"He can nick a goal and it is competition for places. It's what we've needed as we didn't have that last season."
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