The 15-year-old rode to second place in the under 16s boys’ race at the regional championships, contested by four counties at Misterton Hall, in Leicestershire, on Sunday.
The result lifted the Alford rider earned another rise in the national rankings, up to eighth.
Jensen went into the event having been battling for two weeks against a dreaded winter sickness bug which badly hampered his training and affected his fitness.
He found the going tough hard the previous weekend in the latest Notts and Derby League event at Derby, having been advised not to compete, and finished ninth.
The following day at Binbrook he mustered the energy to win his fourth Lincs League race of the season and strengthen his hold on the county crown.
At Misterton, Jensen competed among a field of 30 junior riders from Lincolnshire, Leicestershire, Nottinghamshire and Derbyshire.
On paper, he was second-favourite behind his closest rival, a national and European level rider from Sherwood Pines, who sits two places above him in the national rankings and has had the edge in duels between the two so far this season.
The Sherwood Pines rider led the race from the start, with Jensen close behind.
Into the second lap, the Lincolnshire rider found himself 30 seconds behind with the third and fourth-placed riders catching.
At the end of the second lap he made a pit stop and changed to a fresh bike, but resumed the race in fourth.
Jensen quickly made up ground and stormed back into second place, and by lap five following another bike change, he took the bell still half-a-minute behind the leader.
He responded by putting in the fastest lap of any rider in the race to finish a strong second place, just 16 seconds behind the winner to claim the silver medal.
This weekend, Jensen will compete against the top 100 riders in the National League event at York.