Dom Sibley admitted his frustration at getting out for 43 on his return to action after a broken finger, but believes his attritional two-and-a-half hour stay has gone a long way towards proving his readiness for the first Test against New Zealand at Lord's in just under a fortnight's time.

Despite a struggle for runs at the top and tail of the winter campaign in Sri Lanka and India, Sibley is arguably England's first-choice Test opener at present, thanks to a pair of match-defining half-centuries at Galle and Chennai that demonstrated his mental fortitude in hostile conditions.

And those same attributes were once again to the fore on a seam-friendly first day of the LV= County Championship at Chelmsford, where his 120-ball knock outlasted the combined efforts of the rest of Warwickshire's top five, as Peter Siddle led the line for Essex with 4 for 36.

"Some of the balls today nipped as far as some of the balls that spun in the winter," Sibley said. "Obviously I'm disappointed to get out after doing the hard work to get myself in, but on a wicket like that, there was always going to be one with your name on it. So I'm just pleased to spend some time at the crease and keep building towards what's going to be a big summer."

Though Sibley conceded that his finger was not yet at 100%, after sustaining the injury while dropping a slip catch against Nottinghamshire in April, he was hopeful that a day in the field on Friday would give him the final confidence in his recovery that he will need before resuming his place in the England set-up.

"The finger felt good," he said. "It's one of those ones where it can feel alright in the nets - obviously the odd one gets hit a little bit - but on the whole it was really good. It was more my inner thigh and my box that was getting peppered today.

"If I'd tried to play a few more shots on that [pitch], I would have been out a bit quicker," he added. "I realised pretty quickly that it was going to do a little bit, so you just try to defend well, leave well and run really hard between the wickets when you get the opportunity."

Asked how long he thought it would be until he had full confidence in his finger again, Sibley conceded that the big test of his fitness would come in the field, most likely on Friday, given that Warwickshire reached the close of a rain-interrupted day on 159 for 7.

"I don't know, to be honest," he said. "I'm looking forward to getting out in the field and seeing how it is. With fingers, you never really know. it's all about how it feels when you get into match situations, but with the bat I felt confidence in it.

"I'm looking forward to getting out there and, if the weather holds up, getting involved in the field, diving around and have a bit of a crack. We'll see how it goes. I'm excited to get back out there.

"In terms of percentages, it's difficult to tell really. I'm not 100%, it's my first game back, so I felt a little bit nervy, as everyone does after an injury. But I feel pretty close to being there, so I'm feeling confident.

"It's just great to be back," he added. "Obviously it's been frustrating to be injured, but it is what it is and I've tried to make the best out of a bad situation. I've tried to use it as a time to refresh because you've got to seek the positives out of situations that are not ideal."

Despite being out of action for the past month, SIbley was this week named in England's 15-man squad for the two-Test series against New Zealand, and believes he will link up with the squad at Lord's next week with confidence.

"I've tried as hard as I can do with the finger over the last 10 days, but I just feel really excited to be in the squad and I'm really looking forward to getting involved," he said. "Every opportunity to be involved with England is really exciting, and hopefully I'll play a part in some of the Test matches."

In terms of the current match situation, Sibley was hopeful that Warwickshire's lower order could post a total that will be competitive in tough batting conditions, especially with Tim Bresnan unbeaten overnight on 47.

"When winning the toss and batting first, it was one of those ones where you have to assess the wicket as quickly as possible," he said. "We're not in a bad position. The wicket did a fair bit for the bowlers but we battled hard. If we can scrap as hard as possible to get up to 200, that'd be brilliant."