Johnson is still suspended following his arrest on suspicion of sexual activity with a 15-year-old girl.
Downing has first hand experience of Johnson’s abilities from their time together at Middlesbrough, and the Hammer says the Hammers can collect the poinys.
He told the official website:”They’re missing Adam Johnson obviously which is a big boost for us because he’s probably their best player,” he told the West Ham website.
But he added: “Steven Fletcher on his day is a goalscorer, Connor Wickham is also a handful. Other than that we’re pretty strong and we’ve got goalscorers of our own in the team.
“We should have beaten them when we played them at their place. Our own form has been quite good recently. We have to start well and if we play like we did in the second half against Chelsea we’ll win.”