- Create a calculated field, [ROI Filter]: LOOKUP(ATTR([Runner of Interest]),0).
- Drag [ROI Filter] to the Filters shelf, and check 'isROI' to include only that value.
To use the field [Runner of Interest] as the filter would show any selected runner as 1st, as Tableau first filters for the runner and then does the Rank(). Filtering on a field that uses a table calculation (such as LOOKUP) causes the filter to be applied after table calculations (including RANK), and so the rank of the runner is preserved while the other runners are filtered out of the display.
Thanks for your reply, Eric. Unfortunately, when I implement the ROI filter with 'isROI', the other runners disappear and the runner of interest, who was in second place, now goes to first place, so the comparison is lost still (I'm using rank to determine runner placement).
UPDATE: the comparison was only lost when I removed the pill "Runners" showing each runner. So your answer actually works, I just need to hide instead of remove that header. Thanks!