Yorkshire gained a first innings lead of 118 against Hampshire at the Rose Bowl yesterday but their day was marred by two dropped catches at a crucial stage and an injury worry to fast bowler Chris Silverwood.

After his impressive start to the season, Silverwood is in the frame for a place in England's one-day squad this summer but he was forced to limp off for ice-pack treatment on an ankle injury.

His departure was seen by England selector Geoff Miller who was closely monitoring yesterday's play.

"Chris started to feel pain in his ankle while bowling and it will be some time before we know the full extent of the problem," said Geoff Cope, Yorkshire's director of cricket. "It is a bit worrying but if things are not too serious he may bowl in the second innings."

Silverwood was not alone in being discomforted yesterday because Steven Kirby also had to leave the field for a while for back treatment just after a dynamic burst had brought him three wickets for two runs in 14 balls.

Kirby's blast helped reduce Hampshire to 107 for seven when they still required 37 to avoid the follow on but four runs later Ryan Sidebottom failed to hold a low return catch from Shaun Udal and in the following over Darren Gough had Nick Pothas dropped at first slip by Matthew Wood.

The eighth-wicket pair added 47 in nine overs before Udal was the first of two batsmen in consecutive overs from off-spinner Richard Dawson to be caught close in off bat and pad and when last man Alan Mullally was caught behind at 175 Yorkshire were able to claim a first-innings lead of 118.

Wood and Michael Vaughan put on 23 in eight overs to the close to leave Yorkshire 141 in front.

Yorkshire never imagined when they staggered to 128 for seven on the first day that they would end up with 293 but an immaculate century from Michael Lumb and a bruising 72 from Gough got them there.

Continuing their overnight stand of 46 for the eighth wicket they had extended it to a priceless 126 in 30 overs when Gough edged Simon Katich to the wicketkeeper for 72 from just 96 balls with eight fours and three sixes.

Lumb was left with a flawless 115 from 242 deliveries, his third Championship century being laced with 13 fours.