The Durham fast bowler has been sidelined from top-flight international action with a shin injury for several months and could only watch from the sidelines as Sri Lanka held England to a 1-1 draw in their recent Test series.
"I'm just looking forward to playing if it's against Sri Lanka, Pakistan or whoever I'm playing against for Durham. I just want to go out there and play a game of cricket," said Harmison, who took three for 58 in his first England appearance since March during their 38-run One-day International win over Ireland in Belfast on Tuesday.
"I've spent a bit of time on my backside watching television and shouting at the TV when England were playing Sri Lanka. Now I've got the chance to do what I do best and that's to bowl for England."
Understandably, Harmison's radar was a bit wayward against Ireland and he sent down eight wides.
But the 27-year-old charged in quickly enough to suggest that, if he stays injury-free, he could be a key factor for England in their five-match One-day series with Sri Lanka, which starts at Lord's on Saturday, and the subsequent Test campaign against Pakistan.
"I was flying in (against Ireland) and the ball didn't go where I wanted it to go, but I still felt if I bowled quick enough the batsmen would struggle to handle the pace as other international batsmen could.
England, desperate to make sure their strike bowler if fit for the Ashes series in Australia later this year, instructed Durham not to play Harmison in their championship match against Warwickshire last week.
That meant the paceman was able to fly-out to Germany with his friend and star all-rounder Andrew Flintoff, resting for a month with an ankle problem, and watch the England football team's World Cup opener against Paraguay.
Thursday's Twenty20 fixture has been delayed so fans at the Rose Bowl can watch, on a giant screen, England's second World Cup football match, against Trinidad and Tobago.
And Harmison hopes the cricketers many of whom are, like him, avid football fans, can cash in on that enthusiasm and repeat last year's Rose Bowl Twenty20 triumph, England's only previous match in this format, when they beat Australia by 100 runs to set the tone for the subsequent Ashes series.
"Last year was a bit different because it was against Australia, but it's the same situation because if you go well it takes you into the one-day series."
But Harmison insisted the football would not be a distraction from the task at hand. "We'll do out preparation and do what we have to do, but we'll still be supporting England."
Meanwhile the fast bowler's Durham and England team-mate Paul Collingwood, who top-scored for the hosts with 46 in last year's Twenty20, said: "From my point of view, football is big in the north-east so me and Harmy do talk about it a lot.
"The atmosphere is going to be so much better if England can win (against Trinidad) and then they'll hopefully be shouting a bit louder for us on the night," the all-rounder added.
Collingwood, a veteran of 92 one-day internationals, is doubtful with a left thigh strain and England will also make a fitness check on Lancashire seamer Glen Chapple (abdominal strain) before naming their Rose Bowl team.