USD index as we know is negatively correlated to the EURUSD, so as we think that price may unfold a flat pattern on EURUSD, then we also have to be prepared for a possible flat on the USD Index. Here we see a completed wave 3 at the 88.45 level, from where a three-wave rally unfolded as blue wave a. Afterwards, a drop followed, labeled as blue wave b and now a new bounce can be underway as wave c of 4. If price trades as expected, then we will see a retest of the 90.70 level, before final wave 5 of 5) takes over.

USD Index, 4H

Below we have EURUSD and its reversed picture.

EURUSD, 4H

A Flat is a three-wave pattern labeled A-B-C that generally moves sideways. It is corrective, counter-trend and is a very common Elliott pattern.