Ross County and Kilmarnock fought out a goalless Scottish Premier League draw that extended the hosts' unbeaten league run to 39 games.
Iain Vigurs flashed a shot wide and Marc Fitzpatrick could not convert a close-range chance as County pressed.
Killie's Borja Perez threatened with long-range shot just before the break.
Rory McKenzie had the game's best chance in the second half but the Kilmarnock forward could not beat Michael Fraser.
County have conceded only once so far in their debut Scottish Premier League season and they sit fourth in the table, with Killie seventh.
Vigurs let fly from long range and Letheren was relieved as the ball cleared his left-hand post.
At the other end, Liam Kelly's effort was blocked by Scott Boyd.
A Vigurs corner was headed down by Ross Tokely to Alex Cooper, who nodded the loose ball over the bar from eight yards.
Colin McMenamin just failed to connect with Rocco Quinn's inviting cross as County continued to press.
Another Vigurs corner was spilled by Letheran and neither Fitzpatrick or McMenamin could convert the chance.
The visitors threatened towards the end of the second half with Borja testing Fraser from distance.
Kelly's shot deflected off target early in the second half, while Quinn's shot did not dip enough as Killie found themselves under pressure again.
Danny Racchi's free-kick brushed the side net in Kilmarnock's next meaningful attack and McMenamin's header for County suffered a similar fate.
McKenzie went through on goal 14 minutes from the end but Fraser made the block to preserve Ross County's unbeaten record.