MARK Harrity looks set to replace Matt Mason in Worcestershire's line-up tomorrow as they go head-to-head with table topping Somerset.

The Australian quickie, who has had a mixed start to his New Road career since his summer move, is added to the attack at the expense of Mason while Kadeer Ali drops out.

Worcestershire go into the Frizzell County Championship Division Two clash in top form after easily disposing of Derbyshire and victory at Bath will see them leapfrog Somerset into top spot.

"It would be a very big win for us," said director of cricket Tom Moody.

"It's nice to cross Somerset with us in a good run of form. I think the two teams are the form ones of the division at present so we are looking forward to a good game."

Worcestershire have two massive one-day games coming up following their trip to Bath as they go to Glamorgan in the National League on Sunday before their Cheltenham & Gloucester Trophy clash at Leicestershire two days later.

"We've got two very important one-day games ahead of us and it's the first opportunity for us to rest Matt Mason who has had a heavy workload so far this season," added Moody.

"Mark Harrity may have had a below par performance in one championship game against Hampshire but before that, in our pre-season games, he was the pick of our attack. We have the utmost confidence in Mark."

Somerset have lost seamer Richard Johnson from their attack following his England call-up and Moody believes that is likely to weaken them.

"Losing a quality bowler like Richard Johnson is a body blow for them," said Moody. "However, I'm sure that, like us, Somerset have ample depth in their squad."

Squad: Peters, Singh, Smith, Hick, Solanki, Hall, Batty, Rhodes, Kabir Ali, Harrity, Hayward, Mason.